Table : Estimated Influenza Disease Burden By Season United States 2010
* Estimates from the 2017-2018, 2018-2019, and 2019-2020 seasons are preliminary and may change as data are finalized.
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Some 136 people were hospitalized for the flu between Oct. 1, 2020, and Jan. 16, 2021, and there were 292 deaths involving influenza during that period, the CDC reported. One child has died.
The flu season is far from over it usually begins in the fall, and peaks between December and February.
But in comparison, 400,000 people were hospitalized for the flu and 22,000 died, including 434 children, during the entire 20192020 season, which the CDC described as severe for kids 4 years old and younger, and for adults 18-49 years old.
The flu activity maps look very different for the same week in January 2020, compared to 2021, with most states reporting minimal activity this year:
In 2020, high or very high flu activity dominated the map:
The change is not surprising since the flu virus spreads through respiratory droplets, similar to the new coronavirus, and people are wearing masks, social distancing and paying attention to hand hygiene to avoid COVID-19, said Dr. Waleed Javaid, director of infection prevention and control at Mount Sinai Downtown in New York.
Fewer people are out and about, and people are even hopefully less likely to be out if they are symptomatic, Maruthur added. In normal years, people who are symptomatic do not typically feel the same need to stay home.
National Center For Health Statistics Mortality Surveillance
Based on NCHS mortality surveillance data available on December 16, 2021, 17.4% of the deaths that occurred during the week ending December 11, 2021 , were due to pneumonia, influenza, and/or COVID-19 . This percentage is above the epidemic threshold of 6.6% for this week. Among the 3,330 PIC deaths reported for this week, 2,569 had COVID-19 listed as an underlying or contributing cause of death on the death certificate, and eight listed influenza, indicating that current PIC mortality is due primarily to COVID-19 and not influenza. The data presented are preliminary and may change as more data are received and processed.
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Background And Results: 20192020 Burden Estimates
Flu activity in the United States during the 20192020 season began to increase in November and was consistently high through January and February. The season was characterized by two consecutive waves of activity, beginning with influenza B viruses and followed by Apdm09 viruses. Overall, influenza Apdm09 viruses were the most commonly reported influenza viruses this season. Activity began to decline in March, perhaps associated with community prevention measures for COVID-19 . The 2019-20 season is described as having moderate severity however, the effect of flu differed by age group and the severity of the season in some age groups was higher. Hospitalization rates among children 0-4 years old and adults 18-49 years old were higher than observed during the 2009 H1N1 pandemic .
CDC estimates that the burden of illness during the 20192020 season was moderate with an estimated 35 million people sick with flu, 16 million visits to a health care provider for flu, 380,000 hospitalizations for flu, and 20,000 flu deaths . The number of cases of flu-related illness, medically attended illnesses, hospitalizations, and deaths were lower than some more recent seasons and similar to other seasons where influenza Apdm09 viruses dominated .
The Claim: The Flu ‘disappeared’
While COVID-19 cases continue to rise nationwide, some on social media claim another virus is slowing down.
“Flu has disappeared from the Earth! Just saying!! Smh,” reads a , which garnered more than 400 likes and 70 shares in two days.
shows the influenza virus on a “missing” poster, claiming it hasn’t been seen since February 2020. The Dec. 23 post received more than 2,400 likes and 500 shares in a week.
But the flu hasn’t gone anywhere, experts say.
“Unfortunately, flu hasnt disappeared from the Earth and has been circulating more widely than at any other time during the pandemic,” said Richard Webby, a faculty member at St. Jude Children’s Research Hospital in Memphis, Tennessee.
USA TODAY reached out to the Facebook users who shared the claim for comment.
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Influenza A Vs Influenza B
Both strains of influenza cause typical flu symptoms, like fever, fatigue, body aches, chills, sore throat, and cough. Its unlikely patients would be able to tell the difference between A or B without a lab test. However, Influenza B is slower to develop, which is why it typically appears later in the season. Its also more likely to impact children and younger adults instead of the elderly. This could explain why more people were infected with the flu earlier in the year over previous years, but the number of hospitalizations and deaths were lower.
Flu Surveillance Data Updates
Were there any updates in the methods for flu surveillance for 2020-2021?
For the 2020-2021 flu season, there were some changes to FluView surveillance methodology.
In addition to state-level data, the influenza-like-illness activity map displayed ILI activity by Core-based Statistical Areas , a U.S. geographic area defined by the Office of Management and Budget that consists of one or more counties anchored by an urban center of at least 10,000 people plus adjacent counties that are socioeconomically tied to the urban center by commuting.
Also, during most flu seasons, state and territorial health departments report the level of geographic spread of flu activity in their jurisdictions each week through the State and Territorial Epidemiologists Report. However, because COVID-19 and influenza have similar symptoms and it is difficult to differentiate the two without laboratory testing, reporting for this system was suspended for the 2020-21 influenza season.
More information on flu surveillance methodology and these updates is available online.
Why was pneumonia, influenza, and COVID-19 mortality data added to FluView Interactive?
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Additional National And International Influenza Surveillance Information
FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics.
National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH.
U.S. State and local influenza surveillance: Select a jurisdiction below to access the latest local influenza information.
Outpatient Respiratory Illness Visits By Age Group
More than 70% of ILINet participants provide both the number of patient visits for respiratory illness and the total number of patient visits for the week broken out by age group. Data from this subset of providers are used to calculate the percentages of patient visits for respiratory illness by age group.
The percentage of visits for respiratory illness reported in ILINet are trending upward for all age groups .
* Effective October 3, 2021 , the ILI definition no longer includes without a known cause other than influenza.
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Flu Has Disappeared For More Than A Year
Mask wearing, social distancing and other steps to stop COVID-19 have also curtailed influenza
Since the novel coronavirus began its global spread, influenza cases reported to the World Health Organization from the Northern and Southern Hemispheres have dropped to minute levels. The reason, epidemiologists think, is that the public health measures taken to keep the coronavirus from spreadingnotably mask wearing and social distancingalso stop the flu. Influenza viruses are transmitted in much the same way as SARS-CoV-2, the virus that causes COVID-19, and they are less effective at jumping from person to person.
As Scientific American reported in November 2020, the drop-off in flu numbers following COVIDs arrival was swift and global. Since then, cases have stayed remarkably low. Theres just no flu circulating, says Greg Poland, who has studied the disease at the Mayo Clinic for decades. The U.S. saw about 700 deaths from influenza during the 20202021 season. In comparison, the Centers for Disease Control and Prevention estimates there were approximately 22,000 U.S. deaths in the prior season and 34,000 deaths two seasons ago.
Public health experts are grateful for the reprieve in cases. If the future includes more hand washing, face covering and temporary social distancing when people become sick, perhaps flu seasons can be less severe, even as health restrictions lift and groups gather together again.
Flu Cases Globally And Nationally Have Dropped Dramatically
According to Scientific American, influenza cases all over the globe have dropped to minuscule levels. Were not seeing nearly the same numbers as we have in previous years because of the health measures in place to help slow the spread of COVID19 hand-washing, mask-wearing, staying home when sick, and socially distancing.
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Cdc Director Warns The Us Is At Risk Of A Severe Flu Season This Year
- CDC influenza experts are concerned that the United States could be at risk for a severe flu season this year, Director Dr. Rochelle Walensky warned Wednesday.
- That’s because the U.S. population may now have reduced immunity against influenza after flu cases reached an all-time low last year, she said.
- Walensky urged Americans to get vaccinated for both Covid and the flu.
Centers for Disease Control and Prevention influenza experts are concerned that the United States could be at risk for a severe flu season this year, Director Dr. Rochelle Walensky warned Wednesday.
That’s because the U.S. population may now have reduced immunity against influenza after seasonal flu cases reached an all-time low last year when large parts of the nation were shut down, Walensky told reporters during a White House press briefing.
During the 2020-2021 flu season, there were very few flu cases, “largely because of masking and physical distancing and other prevention measures put in place for the Covid-19 pandemic,” she said.
There were around 2,000 flu cases last influenza season, according to data reported to the CDC. By comparison, the 2019-2020 flu season saw an estimated 35 million cases, according to the agency.
About 69,000 Americans are currently in inpatient beds with Covid, according to the Department of Health and Human Services.
She said it is safe and effective to get vaccines for Covid and the flu at the same time.
Influenza Virus Still Present
Between Sept. 27, 2020, and April 24, 2021, public health and clinical laboratories reported just 2,038 flu cases, compared to an estimated 38 million cases the season prior, according to the Centers for Disease Control and Prevention.
But the influenza virus didn’t just disappear, and experts say it’s unlikely last year’s low case numbers will be replicated.
“Heading into this Northern Hemisphere winter season, we have seen far more flu activity than we did this time last year, which had many of us worried we were in for a big season,” Webby said in an email. “Outbreaks at universities supported this. A big season is still very much a possibility, but my personal view is that the rampant omicron activity may make it hard for flu to push in and spread widely.
“With increasing social distancing/masking hopefully coming back, this will help keep flu numbers low as well.”
The CDC data on the 2021-22 flu season shows influenza is still very much active.
Since Oct. 3, when this year’s flu season began, more than 17,300 positive influenza cases have been detected in both clinical and public health laboratories, according to the CDC. There were 1,265 people hospitalized for the flu during the week ending Dec. 18, and two pediatric deaths have occurred since the start of the season.
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Who Is Most At Risk Of Dying From The Flu
The CDC has a list of people who are at a higher-than-average risk of getting seriously ill with the flu and even dying of it:
- Adults 65 and up
- Young children
- Young children with neurological disease
Certain health conditions can also put people at a higher risk of severe flu, the CDC says, including:
- Chronic kidney disease
The flu tends to kill people at the extremes of age: very young and very old, Dr. Adalja says. The very young and the old may have very low physiological reserve when it comes to fighting influenza off.
Final Flu Season Metrics 2020/21
Each flu season, the CDC tracks a few important metrics that help tell the story of how severe the current flu season is compared to previous seasons. Here are a few numbers to sum up the 2020/2021 flu season, running from October 1, 2020 to April 1, 2021.
Mortality – The PIC mortality rate is the rate of deaths attributed to pneumonia, influenza, or COVID-19. This year, the majority of PIC deaths were due to COVID-19. 646 deaths were attributed to the flu.
Pediatric Deaths – Pediatric deaths are the number of deaths of people under the age of 18. In 2019/20, there were 195 pediatric deaths. There was one pediatric death during the 2020/21 season.
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A Sharp Drop In Flu Cases During Covid
The Centers for Disease Control and Prevention recently reported that it had logged 1,316 positive flu cases in its surveillance network between September 2020 and the end of January 2021. During that same period last year, the CDC had recorded nearly 130,000 cases.
Stephen Kissler, a research fellow in the Department of Immunology and Infectious Diseases at Harvard T.H. Chan School of Public Health, said in a February 11, 2021 Vox article that while more people received a flu vaccine this year, the sharp drop in cases was probably largely driven by mask-wearing and distancing. Kissler suggested that wearing masks in the future could be an effective way of helping control flu outbreaks. Wearing masks in the wintertime, I think its something that might be here to stay, he said.
Kissler also discussed how lower flu prevalence this year creates uncertainties about how the virus will evolve in the future. We have no idea how obliterating the flu for an entire year affects its evolution, he said. We dont know if its going to be easier to predict next years flu strain, because it hasnt been spreading as much. Or if its going to be a lot harder, because its gone through this really tightevolutionary bottleneck.
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But the major contributor has to do with children, who are usually the great distribution engine for the flu, Schaffner noted. Kids are very contagious because they make more influenza virus than adults and they shed it for longer periods of time.
But during the coronavirus epidemic, many children are either learning from home, or wearing masks and social distancing at school.
Children are not getting infected and not bringing the virus home to their elders, Schaffner said.
Its the reason he thinks the incredibly low flu activity during the coronavirus crisis wont be repeated in the years to come.
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A Look Back: This Season’s Flu Numbers V 2019
The U.S. has reported unusually low flu activity during the 2020-21 season, likely due to COVID-19 pandemic safety measures and reporting issues.
Becker’s has compiled data from the CDC for week 15 of the flu seasons in both 2020 and 2021. The data comes from the agency’s weekly FluView report, with data as of April 11, 2020, and April 17, 2021.
Regional flu activity levels
2019-20: During week 15, New York City and New Jersey reported very high flu activity levels, while eight states and Washington, D.C., reported high activity levels. Moderate flu activity was reported in six states, while flu activity was low in 11 states and minimal in 24.
2020-21: During week 15, all 50 states were reporting minimal levels of flu activity. Washington, D.C., was not included due to insufficient data.
2019-20: A total of 19,845 lab-confirmed flu-associated hospitalizations were reported by FluSurv-NET sites between Oct. 1, 2019, and April 11, 2020, with a cumulative hospitalization rate of 68.3 per 100,000 population.
2020-21: FluSurv-NET sites in 14 states reported 223 lab-confirmed flu hospitalizations between Oct. 1, 2020, and April 17, 2021, for an overall cumulative hospitalization rate of 0.8 per 100,000 population.
2019-20: Two pediatric deaths tied to the flu were reported in week 15 for a total of 168 pediatric deaths as of April 11, 2020.
Flu outpatient visits