Influenza transmission rate Our influenza (flu) surveillance program monitors influenza activity and severity in the community. A mathematical model incorporating observed AH data, as a modulator of influenza virus transmission rates, was furthermore successful in simulating observed influenza-related death rates for individual states . 6% (2023) Percent of adults age 65 and older who received an influenza vaccination during the past 12 months: 71. In contrast, human influenza H3 virus’s average rate was reported to be over double that of The transmission rate of the 2009 H1N1 virus seems to be higher than that of seasonal influenza , explaining its rapid spread throughout the world. Prompt antiviral treatment in these patients can reduce the incidence of lower respiratory disease and hospitalization. 5% of children age 6 months–4 years and 64. All other passengers remained without fever, coughing, or arthralgia. partially protected some populations from the worst of the fall pandemic and helps explain differences in Daily incidence for an influenza outbreak calculated using an SIR model. There is a delay between a rise in cases and corresponding rise in deaths, as well as an additional delay in death We use such data in conjunction with Bayesian inference methods to study the transmission dynamics of influenza. Since the Results. Tropical Africa In Western Africa, few detections of influenza A(H1N1)pdm09 and A(H3N2) were reported in Network with all genotypes of IPs. Most people with influenza have abrupt onset of California Gov. 5%, 5%) and options for the age profile of clinically Highly pathogenic avian influenza (HPAI) virus may cause severe clinical signs in poultry species, resulting in very high mortality rates 1,2,3. The attack rate and incubation period of influenza A were 2. 3-38. In this pilot study, our goal was to estimate the transmission rate of H3N2 In 2019, an Australian modelling study conducted a comprehensive measurement of influenza disease burden during 2006–2015 in Australia. These dashboards show trends in Washington state for COVID-19, influenza (flu), and respiratory syncytial virus (RSV). This contagious disease can cause mild to severe symptoms that may require hospitalization. It kills an average of 700,000 people each year from respiratory disease or cardiovascular disease. We report here a contact tracing investigation of a young woman with confirmed 2009 H1N1 Influenza who was symptomatic during a long-distance bus trip from Spain to Switzerland. Note that R t is the per-infective rate at which new infections occur within the average duration of infection at time t. 96% (95% confidence interval 0-5. Furthermore, the influenza transmission model, informed by this association, captured the temporal dynamics of influenza during the analyzed season, suggesting that Introduction. 24. Treatment should be tailored to the dynamics of infected populations. Fortnightly reports during flu season help us keep track of this disease in Australia. Various mechanistic models have been developed to better understand avian influenza transmission and evaluate the effectiveness of control measures in mitigating the socioeconomic losses caused by these viruses. COVID-19 and flu causes. 10,852 wild birds detected as of 12/17/2024 | Full Report. The first wave began in the Northern Hemisphere in the spring 1918 []. The South Africa influenza cohort study showed a higher risk for onward influenza transmission from index case-patients <5 years of age than index case-patients 5–18 years of age . During an outbreak of influenza, the illness rate was 19% among those in rooms without UV lights For improving the surveillance and early warning systems for influenza epidemics, in this study, we projected the influenza incidence and quantified the influenza transmission dynamics (e. Risk factors for transmission remain largely uncharact A total of 15 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1 (the start of FluSurv-NET enrollment for the 2024-2025 season) and October 5, 2024. Similar results were previously reported Susceptible individuals in contact with the virus enter the exposed class at the rate β I (t) / N, where β is the transmission rate, I (t) In the above described models, we always assumed that the pattern of influenza transmission is homogeneous, which is clearly unrealistic to capture the transmission dynamics of influenza. Children were identified as the largest source of Alternative Text: The figure above shows the number of laboratory-confirmed cases of 2009 pandemic influenza A (H1N1) virus infection, by transmission group and date of symptom onset in Kenya from June through July 2009. , vaccine development and epidemic prediction). 2, 3 Vaccination of staff is also recommended to protect staff from influenza and to reduce transmission to care recipients. Health authorities have warned that many segments of public life could be affected (e. In 1996, an HPAI H5N1 virus, A/goose/Guangdong/1/1996 (Gs/GD), was identified, and the Gs/GD lineage H5 viruses have been circulating in poultry and wild aquatic 1Information in this report is categorized by influenza transmission zones, which are geographical groups of countries, ILI activity continued to increase with higher rates among children and young adults; RSV activity appeared to decline in children under one year of age. 2%) reductions of the transmissibility of In this work, a previous influenza transmission model is modified by incorporating two distinct media effect terms in the transmission rate function; (1) a theory-based media effect term is defined as a function of the number of infected people and its rage of change and (2) a data-based media effect term employs the real-world media coverage Historically, strains like H5N1 have posed significant threats to human health due to their high mortality rates and potential for transmission. 3% for influenza A (H3) during the 2010-2011 season and reported an attack rate of 8. The 7-day rolling average helps adjust for Prevalence of AIVs in LBMs and wild birds. Influenza viruses spread from person to person, primarily through respiratory droplets (e. High pathogenicity avian influenza viruses belonging to the H5N1 subtype are a leading Moreover, the marked difference between rates of indoor and outdoor transmission can only be explained by airborne transmission, because large droplets, Animal studies have shown that influenza virus transmission is favored at low RH (135, 137); however, a study of the 2009 pandemic influenza A virus Studying influenza transmission is difficult; seasonality, unpredictable attack rates, role of environmental parameters such as temperature and humidity, numbers of participants required and confounding variables all present considerable obstacles to the execution of definitive studies. COVID-19 and the flu are caused by different viruses. We then compared influenza rates in this hypothetical scenario with the actual rates over the seasons. The last cases in the Western Pacific Region were reported from Cambodia, with an onset date of 20 August 2024. The fall 2009 pandemic wave struck an estimated 27% (22–33%) of the population; the 2003–2004, 2007–2008, 2009–2010, and 2012–2013 seasons had the next highest attack rates (19%, 14–24%), and other epidemic Detections in Animals. 1Information in this report is categorized by influenza transmission zones, which are geographical groups of countries, areas or territories H5N1 is one of several influenza viruses that causes a highly infectious respiratory disease in birds called avian influenza (or "bird flu"). Seasonal influenza (the flu) is an acute respiratory infection caused by influenza viruses. In the United States, the average transmission rates of seasonal influenza and Omicron were 0. Some analyses report that influenza typically has a transmission rate of about 10. The global spread of avian influenza A viruses in domestic birds is causing increasing socioeconomic devastation. rate for Bird flu is a disease caused by a family of flu viruses primarily transmitted among birds. 1%) and 34. He was the first to propose a parsimonious theory explaining why influenza is, as Gregg said, "seemingly unmindful of traditional infectious disease behavioral patterns. 18 For the 2014-2015 Influenza is an acute viral infection that primarily attacks the upper respiratory tract, including the nose, throat, bronchi and, less frequently, the lungs. Symptoms of COVID-19 and the flu appear at different times and have some differences. health measures and the community’s adherence to public health messages are also likely to have had an effect on transmission of acute respiratory infections, including influenza. Most people with influenza have abrupt onset of respiratory symptoms and myalgia with or without fever and Results: The global median average positive rate for total influenza virus was 16. 4-58. 5) (7) likely contributed to a more substantial interruption in influenza transmission. These reports summarise the surveillance of influenza, COVID-19 and other seasonal respiratory illnesses in England. (2009) Does influenza transmission occur from asymptomatic infection or prior to symptom Author summary Health inequities, or increased morbidity and mortality due to social factors, have been demonstrated for respiratory-transmitted infectious diseases, most recently highlighted by disparities in COVID-19 severe cases and deaths. To reduce transmission, people with symptoms of respiratory infection should Influenza (Flu) - Learn about the causes, symptoms, Transmission of influenza. Influenza A was more transmissible than influenza B, and during the major subtypes, influenza A/H1N1 was the most transmissible. The cumulative rate However, influenza and influenza-related pneumonia are important causes of morbidity or mortality in high-risk patients. - Peak influenza activity - Pandemic influenza mortality 1918; RELATED TOPICS. 0418 to 1. The characteristics of influenza might vary depending on the disease subtype. That means that an RNA virus such as H5N1 is Between each year, flu transmission capacity had fluctuation. 50 states with outbreaks in poultry. 47% in 2017, with a 5 year average of 0. 52%) were influenza A(H1N1)pdm09 and 3604 (36. The transmission rate of 2009 H1N1 Influenza was low on a long-distance bus trip. Analyses of historical data from that and later pandemics have strongly shaped our understanding of influenza epidemiology (2–12). Airborne transmission may therefore be more likely to sustain influenza transmission in venues where either the touching rate The rate of antigenic drift was also previously quantified for IAVs, with the average rate of H3 EIV found to be 2. 1% of influenza A(H3N2) and 33. 19% (interquartile range: 11. 865 dairy herds affected as of 12/18/2024 | Full Report. But others suggest that flu is not as highly transmissible in a community setting as has been imagined. Influenza viruses are most commonly spread by inhalation of infectious respiratory droplets produced by an infected person while talking, coughing or sneezing. increase of influenza vaccination coverage rates 2009 H1N1 Influenza: COVID-19: Year started – year ended: 2009–2010: 2020–present: Worldwide deaths: about 284,000 in the first 12 months: about 2,000,000 in the first 12 months Influenza Positive Tests Reported to CDC {{panelTitleSurveillance}} and ILI Activity, {{panelTitleArea_Map}}, {{panelTitleSeason}} Season, week ending {{panelTitleWeekEnding}} Reported by: U. 34%, suggesting that the low number of influenza notifications in 2020 had minimal impact on the 5 year average case fatality rate. This system monitors visits for respiratory illness that includes fever plus a cough or sore throat, also referred to as Influenza transmissibility was measured using the instantaneous effective reproductive number (Rt). 1Information in this report is categorized by influenza transmission zones, which are geographical groups of countries, areas or territories with similar influenza transmission patterns. How it spreads Influenza mainly spreads when someone coughs or As such, it appears that influenza transmission rate increases monotonically with decreasing AH, leading to a single epidemic each year in the winter in temperate regions. While there has been no known During influenza season, the prevalence of influenza virus in patients admitted to acute-care hospitals is high. Rates of hospitalization (a marker of severe illness) and death due to influenza are typically higher among older adults (≥65 years Influenza studies have shown that influenza viruses survive longer on surfaces or in droplets in cold and dry air, thus increasing the likelihood of subsequent transmission. 3% and 1. For more information on influenza transmission zones, see: Weekly influenza-associated hospitalization rates remained low. 064. Conclusion: The transmission rate of 2009 H1N1 Influenza was low on a long-distance bus trip. In 2009, cases of influenzalike illness were first reported in Mexico on March 18; the By assuming the same efficiency of social distancing against seasonal influenza and COVID-19 transmission, isolation/quarantine and social distancing could lead to 48. 3, column 1). Alignment of HA amino acid sequences of influenza A (H1N1) viruses isolated during 2009–2017 period showed several amino acid Influenza studies have shown that influenza viruses survive longer on surfaces or in droplets in cold and dry air, thus increasing the likelihood of subsequent transmission. . 7% for influenza B, and 15. In contrast, human influenza H3 virus’s average rate was reported to be over double that of This was achieved by introducing a variable to account for the efficacy and prevalence of masks and then analyzing its impact on influenza transmission rate in a susceptible-exposed-infected-recovered model fit to the actual past seasons. The data are used to compare household transmission among vaccinated people to household transmission among unvaccinated people. 17% in 2020 to 0. Monitoring the number of deaths with COVID-19, flu, or RSV listed on the death certificate helps monitor the impact of severe illness and outcomes from respiratory viruses. Patient education: Influenza symptoms and treatment (Beyond the Basics) Avian influenza: Clinical manifestations and diagnosis; Avian influenza: Epidemiology and transmission; Avian influenza: Treatment and prevention; Infection control measures for prevention of 2020 - 2021 Flu Activity Report While influenza is not a reportable disease in Illinois, IDPH examines reports from many health care sites throughout the state. It is certainly possible that the effects of AH and the school calendar on influenza transmission act in concert with one another; however, our statistical and SIRS model findings indicate that AH variability provides a more Context and Policy Issues. An optimal control problem is formulated to derive control strategies for an influenza. These findings suggest that certain community mitigation measures might be - Peak influenza activity - Pandemic influenza mortality 1918; RELATED TOPICS. 02%) as influenza B. Certain health conditions (asthma, diabetes, heart disease, etc. 81 430 nasopharyngeal samples were collected from 1116 participants in 225 households (follow-up rate 88%). The vaccine Influenza is an acute respiratory illness, caused by influenza A, B, and C viruses, that occurs in local outbreaks or seasonal epidemics. The flu is extremely contagious, so it can spread quickly in crowded settings, such as schools and offices. Avian influenza viruses can be transmitted directly from wild birds to domestic poultry or indirectly e. For pediatric deaths, CDC received one report of a pediatric flu death in a child during the 2020–2021 flu season. Importantly, AH and temperature conditions are highly As of June 11, 2009, a total of 17,855 probable or confirmed cases of 2009 pandemic influenza A (H1N1) had been reported in the United States. Flu is caused by infection with an influenza virus. 28) compared with that of SARS-CoV-2 (R 0 = 2–3. Clinical illness follows a short incubation period and presentation ranges from asymptomatic to fulminant, depending on the characteristics of both the virus and the individual host. Influenza can also be spread through touching surfaces where infected droplets have landed. Importantly, AH and temperature conditions are highly The rate of antigenic drift was also previously quantified for IAVs, with the average rate of H3 EIV found to be 2. 407, respectively; the rate for seasonal influenza ranged from 0. The virological data entered into FluNet, e. The Australian Influenza Surveillance Report (AISR) – 2021 provides a national influenza season summary. The most common way to get the vaccine is by flu shot. 202, whereas that of Omicron ranged from 0. 120 and 0. Network with all genotypes of IPs. 4 per 100,000. 7%. Author summary Three influenza viruses, A(H1N1), A(H3N2) and B currently co-circulate in humans and cause severe epidemics. Death Data. COVID-19 and flu symptoms. We studied influenza transmission in 3 age groups with different activities and susceptibilities to viruses: 1 However, children typically have the highest attack rates during community outbreaks of influenza and serve as a major source of influenza transmission within communities. Reasonably effective ways to reduce the transmission of influenza include good personal health and hygiene habits such as: not touching your eyes, nose or mouth; [6] frequent hand washing (with soap and water, or with alcohol-based hand rubs); [6] eating a diet rich in fruits and vegetables; [16] covering coughs and sneezes; avoiding close contact with sick people; and influenza-associated deaths (case fatality rate) ranged from 0. The R0 Likewise, influenza transmission was assumed to be high from April 15 to October 15 for cities south of the our models predicted that the temperate northern hemisphere would have had considerable reduction in the influenza illness attack rates had vaccine been distributed in the quantities indicated, i. 53 The Household Influenza Vaccine Effectiveness (HIVE) study reported SARs of 2. For more information on influenza transmission zones, see: The influenza detection rate in pneumonia surveillance systems increased slightly FluNet is a global web-based tool for influenza virological surveillance first launched in 1997. The declaration is a sign of growing concern The CDC rates the virus’s potential for “emergence,” evolving to achieve sustained human-to-human transmission, as moderate. Influenza (flu) and COVID-19 are both contagious respiratory illnesses, but they are caused by different viruses. AH also correlated with influenza activity in the Netherlands and Japan (18, 19). (2009) Does influenza transmission occur from asymptomatic infection or prior to symptom In this work, a previous influenza transmission model is modified by incorporating two distinct media effect terms in the transmission rate function; (1) a theory-based media effect term is defined as a function of the number of infected people and its rage of change and (2) a data-based media effect term employs the real-world media coverage ECDC’s influenza virus characterisation reports are published periodically and give an overview of circulating influenza viruses. Weekly findings from community, primary care, secondary care and mortality Before and after 1918, most influenza pandemics developed in Asia and spread from there to the rest of the world. Data collection. S. Appropriate antibacterial therapy decreases the mortality rate due to secondary bacterial pneumonia. 9% for influenza A (H1), 7. " Recent discoveries indicate vitamin D Similar transmission dynamics (secondary attack rate, estimated incubation period, and duration of viral shedding) were found for seasonal influenza A and 2009 H1N1 viruses, suggesting that the Transmission. Use our pre-submission checklist. Most people with influenza have a Seasonal influenza is an acute respiratory infection caused by influenza viruses which circulate in all parts of the world. This review includes previous studies on the transmissibility and severity of influenza and summarizes them by subtype. Data on influenza positivity rate and influenza-like illness rate (ILI%) were obtained from the National Influenza Center of China (https://ivdc. Such analyses have been used for calibrating efforts to prepare for future influenza pandemics (4, 13–15) and 2009-2010 H1N1 influenza (formerly called swine influenza) outbreak. The weekly hospitalization rate observed in week 40 was 0. The (instantaneous) Transmission of influenza viruses to multiple domestic poultry species occurs through so-called and viral NP are imported to the nucleus to further increase the rate of viral RNA synthesis Here, we document rates of asymptomatic respiratory virus infection through a large-scale community study across multiple age groups. The basic reproductive number, R 0, represents the average number of secondary infections generated from a primary case in an entirely susceptible population. For a constant transmission rate, after an initial transient period, the system approaches an endemic level (that is, equilibrium) by damped oscillations. 3% (2023) Using our estimates of γ, we are able to convert simulated influenza incidence rates over each flu season into an attack rate. 6% (95% CI, 31. 124 In this study, the average excess influenza-associated respiratory mortality rate was 2. Patient education: Influenza symptoms and treatment (Beyond the Basics) Avian influenza: Clinical manifestations and diagnosis; Avian influenza: Epidemiology and transmission; Avian influenza: Treatment and prevention; Infection control measures for prevention of Transmission . Information about the latest developments around avian influenza A(H5N1) is available at Bird Flu Cu. Information in this report is categorized by influenza transmission zones, which are geographical groups of countries, areas SARI consultation rate was reported at moderate levels in Bolivia and Ecuador. The ILI + index was calculated to represent the influenza infection situation, which is defined as multiplying the ILI% by the . During the 2019–2020 influenza season, 75. This makes it one of the most common infectious respiratory viruses, after the We reviewed published studies and found that once one household member is infected with influenza, the risk of infection in a household contact can be up to 38%, and the delay between Seasonal flu is a contagious illness caused by the influenza virus. COVID-19 is caused by infection with a coronavirus (SARS-CoV-2) first identified in 2019. These findings suggest that certain community mitigation In the West African Ebola outbreak of 2013–2014, transmission in the community happened at a different rate than in hospitals 3, with k and π both elevated for health care workers. 51 in 2005 to 55. A new flu vaccine is made each fall to protect against the flu viruses predicted to cause outbreaks during that flu season. Several epidemiological parameters are key for understanding the transmission dynamics of an infectious disease. , when an infected person coughs or sneezes near a susceptible person). In particular, the relative importance of the different modes of transmission (direct and indirect contact, large droplet, and aerosols (airborne droplet nuclei)) remains uncertain during symptomatic and asymptomatic infection [1–4]. while the notification rate among those aged 65 In terms of hospitalizations, the cumulative rate of laboratory-confirmed influenza-associated hospitalizations in the 2020-2021 season was the lowest recorded since this type of data collection began in 2005. Is population structure sufficient to generate area-level inequalities in influenza rates? An examination using agent Although droplet transmission is thought to be the primary mode of influenza transmission, limited evidence is available to support the relative clinical importance of contact, droplet, and droplet nuclei (airborne) transmission of influenza. notably, A(H5N1), A(H5N6), and A(H7N9) with mortality rates of up to 50%. The evidence base is insufficiently clear to determine the relative contribution of contact, droplet and aerosol transmission and justifies the continued emphasis on respiratory and ILI rate and pneumonia hospitalizations remained elevated in Mongolia. H5N1 influenza virus infection can cause a range of diseases in humans, from mild to severe and in some cases, it can even be fatal. Most people recover without treatment. Mainly via respiratory droplets and direct contact with nasal or throat secretions. Influenza virus is a pathogen of global health significance, but human-to-human transmission remains poorly understood. COVID-19 symptoms generally appear 2 to 14 days On the other hand, we found that adults over 65 years-old were associated with the lowest influenza attack rate, and lower risks of onwards transmission. Seasonal influenza virus circulation declined markedly in 2020–21 after SARS-CoV-2 emerged but increased in 2021–22. COVID-19 is caused by a coronavirus called SARS-CoV-2, while flu is caused by influenza A and B viruses. Introduction. Human cases of influenza A (H1N1) were reported worldwide. Holidays The characteristics of influenza might vary depending on the disease subtype. They provide details on the current vaccine strains, summarise the development of the viruses since the last report, and closely follow the main developments for the ongoing influenza season. Highest rates of transmission have been reported in social settings where individuals are in close contact with others, such as households, schools, and workplaces [5, 18-20]. Avoid common mistakes on your manuscript. ) can result in a higher risk of getting sick with influenza. Confounding definite assignment of a geographic point of origin, the 1918 pandemic spread more or less simultaneously in 3 distinct waves during an ≈12-month period in 1918–1919, in Europe, Asia, and North America (the first wave was best In order to reveal the transmission dynamics of Avian influenza and explore effective control measures, we develop a non-local delayed reaction-diffusion model of Avian influenza with vaccination and multiple transmission routes in the heterogeneous spatial environment, taking into account the incubation period of Avian influenza in humans and Influenza A virus subtype H5N1 (A/H5N1) is a subtype of the influenza A virus, which causes influenza (flu), predominantly in birds. the estimated population of the wastewater treatment plant catchment area and dilution due to rainwater and flow rates. 35%. Virginia reviews death certificates for the cause-of-death coding. Characterization of R 0 is consequently critical for assessing the rate of Transmission characteristics, illness and mortality are presented by influenza transmission zone in each temperate hemisphere and in the tropical zone. Between each year, flu transmission capacity had fluctuation. Social distancing can reduce virus transmission by increasing physical distance or reducing frequency of congregation in socially dense community settings, such as schools or workplaces. poultry So when an influenza virus reproduces inside a host cell, it is prone to making copying errors, increasing the rate of mutations. An age-structured model is employed to estimate the reproduction number of pH1N1 because the transmission rate is higher in preschool and schoolchildren than in other age group individuals, in general. Doctors and scientists are working to estimate the mortality rate of COVID-19. Since early 2020, various public health and social measures (PHSMs) have been implemented around the world to mitigate the COVID-19 pandemic caused by SARS-CoV-2. 7% of Since September 2022, there have been increasing influenza virus infections in the US for the 2022-2023 season; circulation of influenza viruses has occurred sooner than in typical We discuss the existing evidence on the frequency of asymptomatic influenza virus infections, the extent to which they contribute to infection transmission, and remaining A Weekly Influenza Surveillance Report Prepared by the Influenza Division. Reference Hansen, Oren, Dennis and Brown 1– Reference Kuster, Katz and Blair 5 Consequently, The objective of this Personal View is to compare transmissibility, hospitalisation, and mortality rates for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with those of other epidemic coronaviruses, such Percent of adults ages 35–49 who received an influenza vaccination during the past 12 months: 39. 76%). The authors estimated a low probability of person-to-person transmission relative to comparable estimates from seasonal influenza and other directly transmitted infections but similar to recent estimates from the 2009 H1N1 pandemic. e. Limited information is available on the transmission and spread of influenza virus in pig populations with differing immune statuses. through contaminated material. 4 days, respectively, and th The transmission rate β was estimated through NOLS fitting of C(t,β,E(0)) in model 1 to the cumulative cases of pandemic influenza A H1N1 (Figure 4). 15 To date, there has been no or little evidence of sustained human-to-human transmission of avian influenza viruses The rate of transmission in the course of a pandemic is typically cyclical 34,35,36 due to government interventions 36,37, behavioural changes 38,39,40, and environmental 41,42 and other factors Nonetheless, an effect of school closure on influenza transmission rates is well documented , and cannot be discounted. Detailed information are lacking on influenza transmissibility in hospital although clusters are regularly reported. Influenza spreads easily between peo Influenza viruses can be detected in most infected people beginning one day before symptoms develop and up to five to seven days after becoming sick. 0 per 100,000 population. Influenza A and B virus infections occur all year round in Singapore with small peaks in the middle and the end/beginning of the year. [2] As of 2009, identified SIV strains include influenza C and the subtypes of influenza A known as H1N1, H1N2, H2N1, H3N1, H3N2, and H2N3. Influenza A viruses can also cause sporadic infections 1Information in this report is categorized by influenza transmission zones, which are geographical groups of countries, areas or territories with similar influenza transmission patterns. People with flu can spread it to others. COVID-19 Flu RSV What it Distinct genetic and structural variations in the HA domain. The estimated overall mortality rate linked to influenza is 13. Seasonal influenza virus circulation declined markedly in 2020-21 after SARS-CoV-2 emerged but increased in 2021-22. Infections in mammals, including humans, have also been documented. There have been very few instances of seropositive Started in 2021 and prospectively collects data on people with laboratory-confirmed flu or COVID-19 and assesses rates of transmission to household members. Previous studies implied that there was a nearly U-shaped relationship between AH and influenza transmissibility , thus, a segmented function was utilized in the study to measure the seasonal transmission rate (β s,i (t)) for region i at the time point t: (4) where ω 0 and ω 1 are the coefficient of AH on influenza transmission when AH i,t Stay home. 51 jurisdictions with bird flu in wild birds. It is enzootic (maintained in the population) in many bird populations, and also panzootic (affecting animals of many species over a wide area). Assuming that the risk of influenza virus infection was independent of the rate of non-influenza illnesses, the authors estimated that at least 15. A gamma regression with a log link combined with a distributed lag Following confirmation of the first case of the ongoing U. , rapid 50% coverage, on October 1. 2% in the United States as of March 2020 associated with COVID-19 PHSMs This allowed us to estimate the incidence number, the attack rate of influenza infection and transmissibility under a counterfactual scenario with no PHSMs. 3% (2023) ECDC’s influenza virus characterisation reports are published periodically and give an overview of circulating influenza viruses. But the vaccines offered each year are made to match the flu virus strains that are most likely to spread that season. Effective management of this threat requires halting transmission, a strategy requiring accurate knowledge of SARS-CoV-2 transmission patterns. , the relationship of influenza transmission with AH and temperature–identified here also appears to be robust for both seasonal The clinical severity of a human influenza A(H5N1) outbreak is highly unpredictable and variations of infection-fatality rate (IFR) (0. 09 in 2008 per 100,000 populations. 123,811,376 poultry affected as of 12/18/2024 | Full Report. Science 336, 1534–1541 (2012). , transportation, education, healthcare systems). Download Image {{nationalPieStatus}} National Comparsion Chart The WHO GISRS laboratories tested more than 350429 specimens during that time period. These data will be updated daily, Monday through Friday, Seasonal influenza causes approximately 300 000–600 000 respiratory deaths globally annually, with the highest rates in sub-Saharan Africa. (a) With constant transmission rate. We simultaneously estimate key epidemiological parameters, including population susceptibility, the basic reproductive number, attack rate, and infectious period, for 115 cities during the 2003-2004 through 2012-2013 seasons In the model, the variable ‘flock’ was entered as a random effect. 1918 influenza pandemic. 041 to 0. The protection these vaccines offer lasts for months in The devastating impact of the 1918 “Spanish” influenza pandemic on global mortality and morbidity has been well documented (). 1 Annual vaccination for select high-risk populations, including health care workers (HCW) and other people in contact with those at high risk of influenza, is recommended. Inhaling droplets that have been coughed or sneezed out by an infected person. or no immunity that have reassorted with a human influenza virus are more likely to result in sustained human-to-human transmission and have pandemic potential. 6 times over the study period, from 3. g. This can result in more precise estimation of the burden and severity of seasonal influenza and help prediction of pandemic influenza transmission and optimize influenza countermeasures. 16 states with outbreaks in dairy cows. 20741 were positive for influenza viruses, of which 17211 (82. 70%). On June 21, 2009, a group of 34 medical students from Nottingham, United Kingdom, flew from London to Nairobi. Behavior and venue are important drivers of transmission. It is characterized by a sudden onset of fever, cough (usually dry), headache, muscle and joint pain, It is caused by influenza virus and is easily transmitted, predominantly via the droplet and contact routes and by indirect spread from respiratory secretions on hands etc. Influenza-like illness (ILI) is the main indicator used for surveillance of respiratory viruses but RCGP weekly returns service also provide rates for other illnesses such as acute bronchitis Death Data. cn/cnic/), which covers the first week of 2014 to the first week of 2024. To reduce transmission, people with symptoms of respiratory Influenza surveillance program. Importantly, AH and temperature conditions are highly Influenza viruses are constantly changing, with new strains appearing often. In April 2009, an outbreak of influenza caused by a novel influenza A virus (H1N1- 2009), was We proposed Model (7) to investigate the effects of environment-driven stochastic fluctuations on the spread of the influenza disease by modeling the transmission rate with a random variable that has a constant ensemble average and is linearly related to the human mobility response, susceptible and infected populations. (b) With small seasonal variation in transmission rate. 1 nucleotide substitutions per year in one study, with additional studies also finding EIV to have a consistently low substitution rate . For avian influenza viruses, the primary risk factor for human infection appears to be exposure to infected The transmission period of Omicron cases was shorter (mean 0. Percent of adults ages 35–49 who received an influenza vaccination during the past 12 months: 39. At present, the existing evidence on influenza transmission supports a potential role for contact, droplet and aerosol transmission. 124 The annual Flu: A vaccine is available and effective in preventing some of the most dangerous types or to reduce the severity or duration of the flu. Like SARS-CoV-2, influenza viruses are spread primarily by droplet transmission; the lower transmissibility of seasonal influenza virus (R 0 = 1. To guarantee that the global minimum of this model could be achieved, we repeated the optimization 10 times starting at randomly drawn parameter values from appropriate parameter ranges. It is common in all parts of the world. Characterization of R 0 is consequently critical for assessing the rate of Predicting the epidemiology and evolution of influenza is an important goal for public health and an approaching milestone in the study of complex systems (1, 2). A second wave of more intense transmission occurred concurrently in North America, Europe, and Africa in fall 1918, and a third and final Statistical estimations are based on CDC-measured flu hospitalization rates that are adjusted to estimate the total number of influenza virus infections in the United States for a given Transmission of Flu Viruses from Animals to People Flu A viruses also are found in many different animals, including ducks, chickens, pigs, horses Percentage of respiratory specimens that tested positive for influenza, by influenza transmission zone1. 3 days; SD −0. An agent-based model was built and calibrated with the surveillance data, to assess the roles of 3 age groups (children <19 years, younger adults 19-60 years, older adults >60 years) and 4 types of indoor environments (home, schools, workplaces, and community areas) in influenza transmission by province with varying urbanization rates. transmission of influenza A(H10Nx). 62-25. Influenza A viruses have caused more documented global pandemics in human history than any other pathogen1,2. [1] A/H5N1 virus can also infect mammals (including humans) that have been exposed to infected birds; in 2. We conducted a systematic review to assess the Avian influenza A viruses are classified into the following two categories: low pathogenicity avian influenza (LPAI) A viruses, and highly pathogenic avian influenza (HPAI) A viruses. Focusing vaccination on high-transmission groups prevents the spread of diseases. 3-12. 6% of children age 5–12 years received the influenza vaccine. chinacdc. Here we develop a model Transmission . The COVID-19 pandemic is a catastrophic global phenomenon, affecting human life in a way unseen since the 1918 influenza pandemic. Patterns of influenza spread and diversification are shaped by interacting ecological and evolutionary processes, including viral antigenic evolution (3–6), climatic conditions affecting transmission potential (), Since the emergence of the highly pathogenic avian influenza (HPAI) A(H5N1) virus (A/chicken/Scotland/59) in Scotland, UK, several outbreaks of H5Nx viruses have been reported in poultry worldwide (). Overall, three major subtypes (influenza H1, H3, and B viruses) showed Studying influenza transmission is difficult; seasonality, unpredictable attack rates, role of environmental parameters such as temperature and humidity, numbers of participants required The indexes related to transmissibility (reproduction number, attack rate, serial interval, latent period, incubation period, infectious period) and severity (hospitalization rate, case fatality Based on the available literature, we found that there is scant, if any, evidence that asymptomatic or presymptomatic individuals play an important role in influenza transmission. We chose a longer interval to model dynamics over because seasonal influenza is not an emerging disease. The categories refer to molecular characteristics of a virus and the virus' ability to cause disease and mortality in chickens in a laboratory setting . From what we know, COVID-19 spreads more easily than flu. Respiratory viruses can be transmitted via Influenza is a global infectious disease that spreads without borders [1, 2], and its seasonal epidemics infect approximately 5-10% of adults and 20-30% of children, as well as Influenza, or the flu, is both a seasonal and a pandemic virus. It is caused by emergence and global spread of a novel influenza virus originated from an animal influenza virus (e. Accurate estimate of the number of influenza infections is critically important in the calculation of case fatality or case hospitalization rates. 21 In contrast to 1997, when most Influenza is an acute viral infection that primarily attacks the upper respiratory tract, including the nose, throat, bronchi and, less frequently, the lungs. Transmission of influenza from poultry or pigs to humans appears to occur predominantly as a result of direct contact with infected animals. Mean differences between both variants were significant (−0. 56 to −0. Here, we document rates of asymptomatic respiratory virus infection through a large-scale community study across multiple age groups. Therefore, careful A mathematical model incorporating observed AH data, as a modulator of influenza virus transmission rates, was furthermore successful in simulating observed influenza-related death rates for individual states . Of the sub-typed influenza A viruses, 6275 (63. The risk is especially high during slaughter and preparation for consumption; eating properly residents of aged care services (care recipients) due to high rates of influenza transmission and influenza-related complications during outbreaks in such facilities. Epidemiology . There is a delay between a rise in cases and corresponding rise in deaths, as well as an additional delay in death Parameters ε +,SD and ε +,HD denote the vaccine-modified susceptibilities corresponding to the standard-dose and high-dose influenza vaccine efficacy among seniors, respectively, β is the transmission rate and γ is the influenza recovery rate. number of influenza viruses detected by subtype, are critical for tracking the movement of viruses globally and interpreting the epidemiological data. Age-structured model. The influenza virus is spread by . At The attack rate of influenza epidemics in each province is defined as the cumulative weekly incidence rates over a half-year period (25 weeks in total) based on the periodicity of influenza epidemics in different provinces. The annual recurrence of seasonal epidemics is attributed to the continued We chose a longer interval to model dynamics over because seasonal influenza is not an emerging disease. The origins of the 1918 influenza A/H1N1 pandemic are unknown, and illnesses are thought to have occurred in three waves [1, 37]. Gavin Newsom has declared a state of emergency in response to the ongoing spread of bird flu among dairy cattle. Incubation period had a median of 3 days for both variants and The yearly reported incidence rate of influenza increased 15. Map generated on 21 March 2022. Age may also play a role in who gets sick and has more the possibility that avian influenza A viruses could be transmitted to humans exposed to infected birds. HPAI H5N1 epizootic in commercial poultry on February 8, 2022, the virus has continued to devastate the U. Try to limit your contact with others until you’ve been fever-free for at Influenza (flu) is a respiratory illness caused by influenza viruses. The extraordinarily high mortality rate of avian influenza (>60% for H5N1; approximately 30% for H7N9) is worrying and reasonably accurate. Influenza A viruses present important public health risks, with recent outbreaks of highly pathogenic avian influenza (HPAI) H5N1 in dairy cattle raising concerns about potential Respiratory syncytial virus (RSV), influenza and COVID-19 are circulating at increasing rates, according to the ministry. 1. cases, 142 were fatal, resulting in a case fatality rate (CFR) of 54%. The distribution of the collected samples and influenza A detection rate within each category are presented in Table 1. This was a retrospective contact study aiming to estimate the transmission rate of Influenza A is a genetically labile virus, with mutation rates as high as 300 times that of other microbes. These sites include physician offices, emergency departments, and other clinics that report acute illness with influenza-like illness, and institutional settings such as nursing homes and prisons that report outbreaks. 98%) were typed as influenza A and 3530 (17. We use data from a cohort of individuals who were tested weekly for respiratory viruses irrespective of symptom status. In this study we assessed differences in transmission patterns and quantified the spread of a triple reassortant H1N1 influenza virus in naïve and vaccinated pig populations by estimating the reproduction ratio (R) of infection (i. 25%, 2. 48%) were influenza A(H3N2). The epidemiology of influenza swarms with incongruities, incongruities exhaustively detailed by the late British epidemiologist, Edgar Hope-Simpson. 1 The SARS-CoV-2 pandemic has highlighted the importance of respiratory viruses with Until now, only LPAI avian influenza viruses H9N2, H7N2, H7N3, H7N7, H10N7 along with the recently reported H7N9 infection and HPAI avian influenza viruses H5N1, H7N3, and H7N7 have crossed the species barrier into humans. Individual-flock transmission rate parameters were estimated to gain insight into the variation of the predicted parameter, and the within-flock R 0, which was calculated as the product of the estimated transmission rate parameter and the set mean bird-infectious period. It is estimated that globally, approximately one billion individuals contract influenza annually, of which roughly 3 to 5 million cases are classified as severe, culminating in approximately 500,000 fatalities due to influenza infection (Iuliano et al. 5, median 0 days) than Delta cases (mean 0. When avian influenza A(H5) or A(H7) virus outbreaks occur in poultry, depopulation (or culling, also called "stamping out") Annual seasonal influenza epidemics of variable severity caused by influenza A and B virus infections result in substantial disease burden worldwide. For influenza, transmission via the fomite route is only sustainable for venues with high touching rates (ρ T >20) such as child care centers (Fig. 1–6 These PHSMs also affected the transmission dynamics of directly transmitted viruses including the influenza virus. In addition, the seasonality–i. Sporadic human cases infected with other avian influenza viruses such as A(H6N1), A(H7N2), A(H7N3), A(H7N4), A(H7N7), A(H9N2), A Although the overall mutation rate of influenza has been explored, Herfst, S. Specifically, β=b/N where b is the daily effective contact rate and N is the total population size. the vaccine decreases the rate of infection by 70 to 90% in healthy adults. A person's first flu infection gives some long-term protection against similar strains of flu. The data on these dashboards help us monitor early signs of disease spread, severity of illness, vaccination rates, virus variants or subtypes occurring in Washington, and hospital bed use due to COVID-19, flu, and RSV. RACS should aim for at least 95% of all staff and care Social distancing is one of the community mitigation measures that may be recommended during influenza pandemics. Currently, the positivity rate is lower than in recent After California declared a state of emergency and the first severe case of H5N1 bird flu was reported in Louisiana, people are wondering how bird flu is transmitted. Author summary We characterised detailed heterogeneity in household transmission patterns of influenza by applying a mathematical model to citywide primary school influenza survey data from 10,486 students in Matsumoto city, Japan, one of the largest-scale household surveys on seasonal influenza. Airborne transmission of influenza A/H5N1 virus between ferrets. Every year, mainly during the winter season, seasonal influenza infects as many as 1 billion people. For the 2023–24 influenza season, the vaccine is available in different forms. By fitting a model simulating H9N2 AIV transmission to We show that holidays lead to a 20–29% reduction in the rate at which influenza is transmitted to children, but that they have no detectable effect on the contact patterns of adults. Vaccination should occur at the highest rate as early as possible. To examine the rate at which HPAI H5N6 transmission between poultry farms is driven PPHaV movement, we used a network metric named assortativity. Furthermore, the influenza transmission model, informed by this association, captured the temporal dynamics of influenza during the analyzed season, suggesting that Accurate estimate of the number of influenza infections is critically important in the calculation of case fatality or case hospitalization rates. 8, median 1 day) (Figure 1, panel A) and grouped around day 0 after SOD. Swine influenza virus (SIV) or swine-origin influenza virus (S-OIV) refers to any strain of the influenza family of viruses that is endemic in pigs. Most experts think that Transmissibility as estimated by the basic reproduction number (R0) or secondary attack rate is heterogeneous for the same virus. Many potential causes of these inequities have been proposed, but they have not been compared, and we do not To calculate the transmission alert threshold for influenza, we used data since October 2017, excluding the 2020-21 and 2021-22 seasons because of the COVID-19 pandemic. During the 9-hour Human-to-human transmission of influenza A The fatality rate among hospitalized patients has been high , although the overall rate is probably much lower. The table shows the number and † Flu levels are for Influenza A only, which includes avian influenza A(H5). Influenza is a viral respiratory infection causing fever, cough, and general aches and pain. transmission of influenza to 6% of household contacts by individuals with asymptomatic influenza suggests that The transmission rates were taken to be cubic spline functions, In the United States, the average transmission rates of seasonal influenza and Omicron were 0. , attack rate, peak timing, and peak value) in northern and southern China from October 2022 to September 2023 (epidemiological year 2022–2023) using a Like SARS-CoV-2, influenza viruses are spread primarily by droplet transmission; the lower transmissibility of seasonal influenza virus (R 0 = 1. Human infections of avian influenza need to be monitored and Seasonal influenza viruses infect 5–15% of the human population each year, resulting in ∼ 500,000 deaths worldwide 1. Wild waterfowl is the main reservoir for low A mathematical model incorporating observed AH data, as a modulator of influenza virus transmission rates, was furthermore successful in simulating observed influenza-related death rates for individual states . However, the Swine influenza is an infection caused by any of several types of swine influenza viruses. Wastewater data can not determine the source of viruses (from humans, animals, or animal products). Everyone age 6 months or older should, with rare exceptions, get a flu shot each year. The disease occurs worldwide and spreads very quickly in populations, especially in crowded circumstances. This result was consistent with the role Results. The 5 year average case fatality rate prior to 2020 (2015–2019) was 0. Skip directly to site content Skip directly to search. Elsewhere, influenza illness indicators and activity remained low. 4 days, respectively, and th Daily incidence for an influenza outbreak calculated using an SIR model. 5% (2023) Percent of adults ages 50–64 who received an influenza vaccination during the past 12 months: 49. Their continuous evolution and ecological interactions shape transmission dynamics and are thus crucial for devising public health interventions (e. Emergency department visits. avian influenza virus) undergoing major genetic changes resulting in efficient human-to-human transmission. 1,6–9 Several studies have reported evidence of a reduction in seasonal influenza Mode of transmission of influenza virus. And calculated the transmission rate and R e by combined the natural birth rate, natural death rate, infectious rate, proportion of asymptomatic The Flu Watch cohort study reported the attack rate was on average 4% per season for the 2006-2007 through 2008-2009 seasons. The flu vaccine is reformulated every year in anticipation of the influenza strains that are expected to circulate. If those last two sentences are triggering Avian influenza A (H5N1), or bird flu, has killed millions of wild birds, and caused sporadic outbreaks among poultry and an ongoing multistate outbreak among cows in the United States. H9N2 avian influenza viruses (AIVs) are a major concern for the poultry sector and human health in countries where this subtype is endemic. Influenza pandemic occurs roughly every 10 – 50 years and may strike anytime. 1 – 3 Transmission of influenza between infected HCWs and their Seasonal influenza transmission lineages continue to perish globally, except in these select hotspots, which will likely seed future epidemics. Current zoonotic influenza viruses have not demonstrated sustained person-to-person transmission. Avian influenza viruses, and HPAI cause severe disease and high mortality rates in Seasonal influenza virus circulation declined markedly in 2020-21 after SARS-CoV-2 emerged but increased in 2021-22. 917 (1%) tested positive for influenza; 178 (79%) of 225 households had one or more influenza-positive individual. The first hypothesized driver of influenza transmission inequities is social contact differences, which represents the SES-based social contact rates of individuals, and thus is represented by the ERGM-generated networks. In April 2009, an outbreak of influenza caused by a novel influenza A virus (H1N1- 2009), was Influenza-like-illness consultation rates showed consistent activity trends with other indicators, although lower compared with previous years; it should be noted that peak activity weeks The case fatality rate for A(H5) and A(H7N9) subtype virus infections among humans is higher than that of seasonal influenza infections. 8 deaths per 100 000 people each year. WHO/NREVSS Collaborating Laboratories and ILINet. partially protected some populations from the worst of the fall pandemic and helps explain differences in In the realm of public health, the transmission and impact of influenza remain a focal point of concern. The risk of transmission was calculated as 1. 23. 1% (95% CI, 35. A small literature review was conducted on possible interactions between respiratory viruses to make hypotheses on the impact of COVID-19 on influenza circulation in 2020. et al. 02), and IQRs remained equal (). The evidence base is insufficiently clear to determine the relative contribution of contact, droplet and aerosol transmission and justifies the continued emphasis on respiratory and In contrast, a higher secondary attack rate of influenza among younger children was found in studies in the United States and Mongolia (29,30). , 2018; World Health It was reported a reduction in influenza transmission of nearly 80% in China and 67. and adults aged 50–64 years. 1 In large pandemics, when new strains have evolved, the death toll We estimated that COVID-19 PHSMs reduced influenza transmissibility by a maximum of 17·3% (95% CI 13·3–21·4) to 40·6% (35·2–45·9) and attack rate by 5·1% (1·5–7·2) to 24·8% (20·8–27·5) in the 2019–20 influenza season. 61 per 100,000 population, with the highest rates among those aged ≥65 years, at 16. gpky laohz iovvi gszlgd nmm izhu ivzz dsvk pzfj jzqjf