Dr. Jay K. Varma is a special contributor to Healthbeat. Public health, explained: Sign up to receive Healthbeat’s free national newsletter here.
In my clinic last week, I began to see the signs of what I have been fearing for months. Two patients came in on the same day with high fever, sore throat, and body aches. Both tested positive for influenza.
While there is nothing remarkable about people getting the flu in the winter, what worries me is the timing and spread. Across New York state, influenza activity is already far higher than it was at this point in recent years. During the week ending Dec. 6, there were more than 12,000 reported flu cases and nearly 1,400 hospitalizations. During the same week last year, there were fewer than 5,000 cases and about 300 hospitalizations. Two years ago, cases were similarly high, but hospitalizations were substantially lower.
This season, influenza is arriving earlier, spreading faster, and sending more people to the hospital. The United States is heading into a flu season that is likely to be worse than what we have experienced in recent winters.
Why this flu season is likely to be severe
Several factors are converging at the same time to increase the likelihood of a severe flu season.
The first factor is viral evolution. The dominant strain right now is influenza A H3N2, and it has accumulated mutations that allow it to partially evade prior immunity. This strain has already driven early and large flu surges in other parts of the northern hemisphere, including Japan, the United Kingdom, and parts of Europe. Some hospitals in those countries reported seeing January level flu activity as early as October.
The second factor is timing. Flu has arrived earlier than usual before health systems have fully prepared and before vaccination campaigns have reached their peak, so the pressure builds faster.
The third factor is behavioral. During the Covid pandemic, many people adopted habits that reduced flu transmission, including masking in crowded indoor spaces, staying home when sick, and improving indoor air quality and ventilation. Most of those practices have faded. At the same time, fewer Americans are getting their annual flu vaccine. Adult flu vaccination coverage has declined over the past several years, particularly among people under 65 who nonetheless have medical conditions that put them at higher risk of complications.
Finally, hospitals are entering this winter with little reserve. Emergency departments, inpatient wards, and intensive care units are operating close to capacity even before seasonal respiratory viruses peak. In that context, a severe flu season can make it much harder for people to get prompt and high-quality care in outpatient and inpatient facilities.
What we know about this year’s flu vaccine
Because of the way influenza viruses mutate and the waning of human immunity over time, the effectiveness of the seasonal flu vaccine varies each winter. Every spring, global experts analyze data and try to predict what influenza strains are likely to circulate in the coming winter. When circulating viruses mutate after those strains are selected, the match between vaccine and virus can be imperfect.
That is what has happened this year. Data from the United Kingdom show that the dominant H3N2 subclade circulating this winter is different from the strain used to produce the northern hemisphere vaccine. Laboratory studies confirm reduced reactivity between the vaccine strain and the circulating virus.
Early vaccine effectiveness data from the UK show that, despite this mismatch, vaccination does reduce severe illness, albeit not as much as we would like. The vaccine reduced emergency department visits and hospital admissions by 72%-75% among children and adolescents and 32%-39% among adults.
This aligns with how I have been counseling patients in my clinic. The flu vaccine does not guarantee that you will avoid infection. What it does is lower the odds that influenza turns into pneumonia, respiratory failure, or a hospital stay – turning a “wild” infection into a “mild” infection.
In a year when hospitals are stretched thin, that difference matters both for individuals and for the entire health system.
What public health agencies can do now
While the Centers for Disease Control and Prevention’s website still recommends annual seasonal flu vaccination for anyone ages 6 months or older, it is unlikely the CDC will be permitted to run advertising this year to promote that recommendation, as it has in years past. Last February, soon after taking office, the new Health and Human Services secretary cancelled the CDC’s 2024-25 flu vaccination campaign.
State and local health departments can fill that gap by promoting flu vaccine through all available channels and enlisting social media influencers to promote it as well. The priority is demographic groups and settings where flu spreads quickly and causes disproportionate harm. Nursing homes, assisted living facilities, long-term care facilities, shelters, jails, and prisons all require targeted vaccination efforts, rapid testing access, and clear infection control guidance.
Clinicians also need reminders about antiviral treatment. Medications like oseltamivir are only effective when started as soon as symptoms begin and primarily benefit populations at highest risk for severe complications, including young children, pregnant people, older adults, and those with chronic medical conditions. Too often, opportunities to reduce severity are missed because testing and treatment are delayed.
What health care facilities can do now
While flu season has begun, hospitals and clinics still have time to bolster their capacity to handle future surges. Bolstering capacity starts with ensuring their staff do not become severely ill from influenza.
Many patients arrive at a facility with one illness, but leave with influenza, because respiratory viruses spread easily inside health facilities. Facilities need to upgrade the completeness of screening patients for respiratory symptoms at initial intake, then isolating and testing patients for influenza and other respiratory viruses. Masking policies that include visitors, especially in patient care areas, remain a simple and effective tool during periods of high respiratory virus circulation. Assessing airflow, upgrading central air filtration, and using portable air purifiers in crowded spaces can reduce viral spread indoors. These improvements benefit patients and staff well beyond this flu season.
What employers can do now
Employers have more influence on flu spread in their offices and communities than they often realize. Providing paid time off for vaccination or offering on-site flu clinics removes a major barrier for many workers. Encouraging employees to stay home when sick and permitting remote work, rather than rewarding them for showing up despite illness, reduces outbreaks in the workplace.
Making high-quality masks available to employees that want to use them, improving ventilation, and offering home test kits are relatively low-cost interventions that can protect workforce health and continuity.
What individuals can do
This will be the first flu season since federal officials instituted severe cuts to infectious diseases and immunization programs across the country. For individuals, this means that it is more important than ever to take pro-active steps to protect your and your family’s health. Get vaccinated if you have not already. Keep high-quality masks and home test kits available in your home. If symptoms start, test early and contact a health care provider if you are at higher risk and may benefit from antiviral treatment.
Dr. Jay K. Varma is a physician and epidemiologist. An expert in the prevention and control of infectious diseases, he has led epidemic responses, developed global and national policies, and implemented large-scale programs that saved hundreds of thousands of lives in Asia, Africa, and the United States.
