Flu activity has changed this season since the onset of COVID-19

The United States has experienced a reduction in influenza cases over the last two years, which may be attributed in part to masking, limited exposure to indoor gatherings and other precautions that the general population took against COVID, according to the CDC. The high rates of flu vaccinations during 2020-2021 may have also contributed to this decrease, as a record number of flu vaccine doses were distributed in the United States during this time, the CDC has said.

However, this reduction in influenza activity over the past two seasons may have also resulted in diminished immunity against the flu among the general population—so this year, with reduced COVID mitigation protocols in place, the country may experience a more severe flu season than in past years. The CDC reported that the number of people hospitalized for the flu between October 1 and October 22 was the highest number of flu-related hospitalizations at that point in the flu season in the last 10 years. At the end of October, preliminary data showed the highest cumulative rates of hospitalizations occurred in people aged 65 and older, followed by children aged 0 to 4 years old. 

Public health experts from the National Foundation of Infectious Diseases (NFID) and the CDC spoke about preparing for the 2022–2023 flu season during an October press conference held by the NFID. 

“Flu is fickle. It’s difficult to predict how serious this next outbreak of influenza this season is going to be,” said NFID Medical Director William Schaffner at the press conference. “But if you wanted a hint, we could look at what happened in the Southern Hemisphere.”

As it happens, the most recent influenza season in Australia and Chile began weeks earlier than usual in both countries. Australian hospitalizations due to influenza were characterized by the highest number of flu cases since 2017; hospitalizations due to pneumonia and influenza were substantially higher than observed in the last two flu seasons, but also lower than in the years before the COVID-19 pandemic.

Vaccination reduces the risk of the flu and its complications

According to the CDC, the best way to reduce the risk of getting the flu and its potentially serious complications is to get a flu vaccine each year. Yet despite the anticipated increase in influenza activity this season, a recent NFID national survey indicated that a lower number of adults are planning to get vaccinated for the flu this year.

In this survey, conducted in August among 1,005 adults aged 18 years and older, 69% agreed that receiving an annual flu shot is the best way to prevent flu-related hospitalizations and deaths; however, 49% said they planned to get vaccinated against the flu this season. Another 41% of survey respondents said they were unsure or had no plans to receive a flu vaccine in the upcoming flu season.

Overall flu vaccination coverage has held steady since 2019, with just over half all people aged six months and older receiving a flu vaccine. So how are the rates of flu vaccinations faring so far in 2022?

Results from another recent survey conducted in early October indicated 21.2% of adults over 18 have had a flu shot this year. However, insurance claims data on flu vaccinations indicates that fewer people are receiving their flu shots at this point in the flu season compared to the same period over the last three years. In mid-October, the rates of flu vaccinations in pharmacies and doctors’ offices were 15% lower than rates at the same time last year.

In addition, a trend noted last year in decreased vaccinations among children and pregnant people appears to be continuing this flu season, based on data reported by the CDC. (Similarly, the rates of COVID vaccination have declined significantly this season, compared to this time in 2021.)

Aside from the potential for reduced flu immunity in the general population, the flu season could be further affected by flu cases in young children who have neither had influenza nor received a flu vaccine. Flu activity frequently rises in school-aged children five years and older, and later spreads to higher risk family members such as infants younger than six months and adults 65 years and older—a trend that appears to be playing out this season.  

The 2022-2023 flu season still has months to go, and only time will tell how severe and long this season will be. The CDC recommends that all eligible people aged six months and older get their flu vaccine as soon as possible—and that vaccination for influenza should continue for as long as the flu season lasts. Children and adults can receive flu vaccines that have been approved for use in their respective age groups. For people aged 65 years and older, the CDC has preferentially recommended adjuvanted or higher dose flu vaccines over standard dose flu vaccines.

Given the early, intense start to the flu season—and the concurrent presence of several other viruses that will put people at further risk for respiratory illnesses—getting vaccinated for the flu and COVID-19 has never been more important than in this season. In planning for upcoming holiday gatherings, it’s important to time your vaccinations in advance; for influenza, it takes about two weeks for the body to create antibodies that provide protection.  

“While we will never exactly know what each flu season will hold, we do know that every year, the best way you can protect yourself and those around you is to get your annual flu vaccine,” Rochelle P. Walensky, MD, MPH, CDC Director, said during the NFID press conference in October. “So I am here to strongly encourage everyone who has not already been vaccinated to find the time and go get vaccinated.”

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