It's that time of year again: Flu season is upon us.
In the United States, flu activity typically starts to increase in October, peaks between December and February, and then begins to decline through April and even May. Flu viruses tend to thrive in the cold, dry conditions of winter. The decrease in temperatures may also affect bacteria-fighting cells in the nose, reducing the power of our immune system to fight the flu and colds.
But in recent years, the usual flu season patterns have been disrupted by the COVID-19 pandemic. The 2020–2021 flu season was unusually mild, likely due to widespread mask-wearing, remote work and school, and social distancing. Flu activity patterns in 2021–2022 and 2022–2023 began to look more like those before the spread of COVID, although the 2022–2023 flu season was considered to be moderately severe. Last flu season, 2023–2024, was also moderately severe, with the timing and intensity of flu activity similar to pre-COVID flu seasons of the past.
With COVID and respiratory syncytial virus (RSV) also in circulation with flu, protecting your health during the fall and winter has become more challenging.
Now that we are well into the fall, what respiratory disease trends can we predict during the 2024–2025 flu season?
Early forecasts for respiratory viruses this fall and winter
In August, the Centers for Disease Control and Prevention (CDC) released a report on their initial outlook for the current respiratory virus season, looking at the potential impact that flu, COVID and RSV may have on public health.
This combined report shows that the CDC anticipated similar or fewer total hospitalizations due to these three viruses compared to the previous season. In a late October update, the CDC continued to uphold their earlier assessment, noting that overall respiratory virus activity remained low at that time.
Predictions for the flu season in fall and winter 2024–2025
Looking specifically at flu activity, as of late October, flu cases have risen slightly since the summer; however, the rates remain below the national baseline.
In its most recent report, the CDC said that it expects that the peak flu-related hospitalization rate will be similar to, or lower than, last flu season’s rate of 8.9 weekly lab-confirmed hospitalizations for every 100,000 people.
The CDC has noted that its outlook reports on respiratory virus season have been based on historical data, modeling of different scenarios and consultations with experts. Ultimately, the impact of the current flu season will depend on the predominant flu strains that circulate over the next few months, as well as the immunity that people have to the flu virus subtypes in circulation and the effectiveness of flu vaccines against those subtypes. Flu vaccines for the 2024–2025 flu season have been updated to match the viruses that are expected to circulate.
“[T]here are a lot of assumptions that go into a projection,” noted CDC Director Mandy Cohen, M.D., M.P.H., at an August press conference. “Say, for example, the number of people who ultimately get vaccinated against flu, COVID, and RSV is lower than expected—then that could mean more hospitalizations, not fewer.”
The Flu Scenario Modeling Hub, which models different scenarios that may occur during the flu season to help with projecting flu season outcomes, recently provided its first round of projections for this season. In reviewing scenarios involving different flu vaccination rates and flu virus subtypes that may circulate this season, the modeling team noted that—depending on the predominant flu virus in circulation—increasing vaccination rates could reduce flu-related hospitalizations by 11% to 12% (approximately 25,000 to 32,000). This could help reduce the burden of care on healthcare systems during respiratory virus season.
Aside from this, flu activity during the Southern Hemisphere flu season, which typically runs from April to September in any given year, may hint at what we can expect in the Northern Hemisphere flu season. In 2024, flu activity in the Southern Hemisphere looked fairly typical compared to pre-COVID and the 2022–2023 flu seasons.
The bottom line: Make a plan for flu prevention
While the flu season may be similar to or milder than last season's, flu can be a serious threat to your health. Getting a seasonal flu vaccination every year is the best way to prevent flu and its potentially severe complications. Although the CDC recommends getting a seasonal flu shot before the end of October, it's not too late to get your flu shot; as long as flu is circulating, vaccination provides protection. It generally takes about two weeks to build up sufficient flu antibodies. If you have questions about flu vaccination, talk to your doctor or pharmacist about it.
Besides getting vaccinated, even everyday actions can make a difference in helping to protect you against flu and other respiratory viruses. These actions include simple things such as avoiding close contact with sick people, staying at home when you’re sick, covering coughs or sneezes, and washing your hands often.
Most people who get the flu will not need medical care or antiviral medication. However, if you develop symptoms of the flu and are at higher risk for serious complications from the flu—or if you become very sick or concerned about your symptoms—call your healthcare provider.
