September 30, 2024 – What is the outlook for COVID-19 and flu this fall and winter? It will likely be much like last yr, experts say.
“We currently expect this flu season to be similar to last year's season,” said Adrienne Keen, PhD, of the CDC's Center for Forecasting and Outbreak Analytics. “We expect this year's peak of the COVID-19 season to be similar to or lower than last year.” The CDC continues to analyze COVID surveillance data from the summer and will update the forecast as more evidence becomes available.
For COVID, that means it won't be as bad as the pandemic years, and for flu, it's a typical pre-pandemic period. But status quo doesn't mean great.
According to the information, up to 75 million people in the USA contracted the flu between October 2023 and April 2024 CDC estimatesresulting in up to 900,000 hospitalizations and between 17,000 and 100,000 deaths. In 2023, approximately 900,000 Americans were hospitalized COVID and 75,000 died.
Other experts agreed with Keen's prediction.
But unknowns — like a fast-spreading COVID variant or a surprising flu strain — could shatter that forecast. Vaccination remains critical, public health officials stress.
Predicting COVID
Two key predictors of how bad an upcoming COVID season will be are the emergence of new variants and the Immunity of the population (Protection against an infectious disease that occurs when a population is immune through vaccination or previous infection).
As new variants increase and immunity declines, “we tend to see an increase in cases,” said Michael T. Osterholm, PhD, MPH, director of the Center for Infectious Disease Research and Policy and professor of public health at the University of Minnesota, Minneapolis. But if the number of variants falls and immunity rises, the outlook is brighter.
The new COVID variant called XEC has been found in at least 25 states. On Friday, the CDC added the variant COVID tracker. It now accounts for 6% of U.S. cases. This was expected because the variant was circulating in Europe, said Amesh Adalja, MD, a senior scientist and infectious disease expert at the Center for Health Security at Johns Hopkins University in Baltimore.
“There will always be a new variant emerging and another variant falling,” he said. “So the fact that this is happening is not surprising.”
Meanwhile, the summer COVID surge has given some people post-infection immunity. “What is likely is that we will see significant population protection for several months based on previous infections and, in some cases, vaccination,” Osterholm said. This means protection against serious illness, hospitalization and death (but not necessarily against infection). That protection could last all yr long or into early next yr, he said.
Andrew Pekosz, PhD, professor and associate chair of molecular microbiology and immunology at Johns Hopkins University in Baltimore, said the timing of this yr's winter surge will likely be barely later than last yr, “peaking shortly after the Christmas/New Year holidays.” .” .”
Last year, weekly COVID hospitalizations peaked the week of December 30, said Justin Lessler, PhD, a professor of epidemiology at the University of North Carolina at Chapel Hill and a member of the COVID-19 Scenario Modeling Hub.
But variants are unpredictable. “There is a possibility that the XEC variant will break out and spread, or not,” Adalja said. On September 28th, the Omicron variant KP.3.1.1 was at the top 58.7% of US cases according to the CDC.
While Adalja agreed that this year's COVID season will likely be like last year, “we have to be prepared for a surge in cases and hospitalizations,” he said, “but to not the purpose of crisis.” A return to lockdowns and social distancing was unlikely, he said.
Still, older adults and other people at higher risk of becoming seriously ill with COVID should consider wearing a mask while traveling, said Rajendram Rajnarayanan, PhD, MSc, an associate professor at the New York Institute of Technology College of Osteopathic Medicine Arkansas State University, Jonesboro.
Flu forecasts
It's difficult to predict flu season so early, said Jeffrey Shaman, PhD, professor of environmental health sciences and professor of climate at Columbia University in New York.
“You can look at the CDC forecast and use it as a very rough guide now,” said Shaman, who won the CDC’s first “Predict the Influenza Season Challenge” in 2014. “Until the flu actually happens, it’s like trying to predict the landfall of a hurricane.” Flu activity persisted low As of September 14 (the most recent data available), according to the CDC.
When flu activity increases, typically in mid-October or November, experts look at the dominant strain, exposure to similar strains in previous years and the suitability of the current flu vaccine for that dominant strain, Shaman said. Vaccine makers must make an educated guess about which strain they are targeting months in advance to allow time for production.
The vaccination rate also plays a role, but this tends to remain constant, said Shaman. According to the CDC, less than half of adults ages 18 and older received a flu shot last year.
Experts are also considering flu patterns in the Southern Hemisphere, where 2024 flu The CDC noted that the activity primarily affected two subtypes of influenza A – H1N1 and H3N2 – and some influenza B.
How well do this year's vaccines and viruses fit together?
The FDA has approved three updated COVID vaccines this fall. Novavax is targeting that JN.1 Strain of SARS-CoV-2, the virus that causes COVID-19. Both mRNA vaccines, Moderna and Pfizer, goal this KP.2, a descendant of JN.1. All three goal the currently prevailing variants, and every is beneficial by the CDC.
The vaccines match well, “although not perfectly, with virtually all circulating variants of SARS-CoV-2,” Pekosz said.
Experts said the shots would protect against the XEC variant.
“XEC and its sublineages are expected to be the dominant fall/winter variant group,” Rajnarayanan said.
This year's flu vaccines, all of them trivalent (Protection against three viruses) targets the three expected circulating strains – H1N1, H3N2 and Influenza B (Victoria), according to the CDC.
People should still get vaccinated, Adalja said, take home tests for flu and COVID and take antiviral medications promptly if needed. The goal mustn't be the established order, but quite fewer hospitalizations and deaths from COVID and flu illnesses, he said.