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As the U.S. heads into the 2024-2025 flu and COVID-19 season, public health experts predict a similar trajectory to last year. Dr. Adrienne Keen of the CDC’s Center for Forecasting and Outbreak Analytics emphasized that this season’s flu peak is expected to resemble last year’s, and the COVID-19 season could be comparable or even less severe.
While the worst pandemic years are behind us, “status quo” does not mean we are in the clear. Last season saw up to 75 million flu cases between October 2023 and April 2024, leading to nearly a million hospitalizations and up to 100,000 deaths. COVID-19 followed a similar toll, with approximately 900,000 hospitalizations and 75,000 deaths.
However, as always, there are unknowns. A new COVID variant or an unexpected influenza strain could still shake up these predictions, making vaccination critical.
Predicting COVID-19
The two main factors shaping COVID-19’s impact this season are new variant cycles and the population’s immunity levels, whether from vaccination or prior infection.
“When new variants rise and immunity wanes, cases surge,” said Dr. Michael T. Osterholm of the University of Minnesota’s Center for Infectious Disease Research and Policy. Conversely, fewer variants and stronger immunity mean a more favorable outlook.
Currently, the XEC COVID variant has emerged in 25 U.S. states, now accounting for 6% of cases. The variant, which first circulated in Europe, is being tracked closely by the CDC. However, its appearance is no surprise, according to Dr. Amesh Adalja of Johns Hopkins University.
“We should always expect new variants to appear,” Adalja noted. While XEC may gain traction, its dominance is not guaranteed. As of late September, Omicron’s KP.3.1.1 strain led in the U.S., making up 58.7% of cases.
Experts remain cautious but optimistic, expecting this year’s peak to follow last year’s pattern, occurring just after the Christmas and New Year holidays. While hospitalizations are likely to increase, “a return to crisis levels or lockdowns is unlikely,” said Adalja. However, those at higher risk, particularly older adults, should still consider masking during travel, advised Dr. Rajendram Rajnarayanan from the New York Institute of Technology.
Flu Season Outlook
Predicting the flu season this early is trickier. “Until flu activity begins, it’s like forecasting a hurricane’s landfall,” said Jeffrey Shaman of Columbia University. Flu activity remains low as of mid-September, with an uptick expected in mid-October or November.
Key indicators of flu severity include the dominant strain, exposure history, and the effectiveness of the current flu vaccine. Vaccine manufacturers make their best guess months ahead to target the right strain for the season, and early data shows that 2024 flu activity has mostly involved influenza A subtypes H1N1 and H3N2, along with some influenza B cases.
Last year, only about half of U.S. adults received a flu shot, a vaccination rate that experts expect to hold steady.
The Role of Vaccination in the Coming Season
This fall, the FDA approved three updated COVID vaccines. Novavax’s formula targets the JN.1 strain, while Moderna and Pfizer’s mRNA vaccines target KP.2. All three aim to combat the most common variants in circulation. These vaccines are well-matched to most circulating strains, offering protection against XEC, expected to be the dominant variant by winter, according to Rajnarayanan.
The flu vaccines also look promising. This year’s trivalent vaccines target the expected strains of H1N1, H3N2, and influenza B (Victoria).
Vaccination, coupled with tools like home testing for flu and COVID, remains key to minimizing hospitalizations and deaths. As Adalja emphasized, “Our goal should not be just to maintain the status quo but to reduce the impact of both flu and COVID.”
Conclusion
As we prepare for the fall and winter respiratory virus season, experts stress vigilance through vaccination and infection prevention. While predictions suggest this year may mirror last, the potential for new COVID variants and flu strains means there are still uncertainties. Maintaining preventive measures and staying up-to-date with vaccines will be essential to safeguarding public health.
