The single most effective way to prevent the flu is getting vaccinated each year. In the 2024–2025 season, the flu vaccine reduced doctor visits and urgent care trips by roughly 50 to 60% in children and 42 to 56% in adults. It also cut hospitalizations by up to 78% in children and 41 to 55% in adults. But vaccination is just one layer of protection. Combining it with a few practical habits can lower your risk even further.
Get Vaccinated at the Right Time
The flu vaccine remains your strongest tool, even in years when the match between the vaccine and circulating strains isn’t perfect. Immunity builds over about two weeks after the shot, and it gradually fades over the following months. That’s why timing matters: September and October are the sweet spot for most people. The CDC recommends everyone be vaccinated by the end of October, before flu activity typically peaks in December through February.
Getting vaccinated too early can be a problem. Adults 65 and older and people in early pregnancy should generally avoid July or August vaccinations, since their protection may decline before the season ends. On the other hand, getting vaccinated late, even in January, still offers meaningful protection if the season runs long. A new vaccine is needed every year because your immune response fades and because the virus itself changes from season to season.
Special Vaccines for Adults 65 and Older
Older adults face the highest risk of severe flu complications, and their immune systems typically produce a weaker response to standard vaccines. That’s why the CDC preferentially recommends high-dose or adjuvanted flu vaccines for people 65 and older. These formulations are designed to trigger a stronger immune response. If you’re in this age group, ask specifically for one of these enhanced options rather than accepting a standard-dose shot.
Keep Indoor Air From Getting Too Dry
The flu virus thrives in dry air. Research on influenza transmission found that low relative humidity, between 20% and 35%, creates the most favorable conditions for the virus to spread. At 80% humidity, transmission was completely blocked. Most heated homes in winter drop well below 40% humidity, which partly explains why flu season overlaps so neatly with cold weather.
A simple hygrometer (available for a few dollars) can tell you where your home sits. Running a humidifier to keep indoor humidity between 40% and 60% makes the air less hospitable to airborne flu particles while staying comfortable and avoiding the mold problems that come with higher levels.
Clean Shared Surfaces Regularly
Flu viruses survive 24 to 48 hours on hard, non-porous surfaces like stainless steel, plastic, and countertops. That means a doorknob, light switch, or shared keyboard touched by someone who’s infectious in the morning can still carry live virus the next day. Fabric and skin hold the virus for shorter periods, but hard surfaces in shared spaces are the bigger concern.
Wiping down high-touch surfaces with a standard disinfectant, especially during flu season, reduces the chance of picking up the virus on your hands and transferring it to your eyes, nose, or mouth. This matters most in offices, kitchens, and bathrooms shared by multiple people.
Wash Your Hands, but Know the Limits
Handwashing is a cornerstone of infection control and protects against many gastrointestinal and respiratory illnesses. That said, a large meta-analysis published in The Lancet found that handwashing with soap did not significantly reduce test-confirmed influenza specifically. The flu spreads heavily through airborne droplets and aerosols, not just hand-to-surface-to-face contact. Wash your hands frequently, especially before eating and after being in public spaces, but don’t rely on handwashing alone as your primary flu defense.
Masks Work, and the Type Matters Less Than You’d Think
Wearing a mask in crowded indoor settings during peak flu season provides a real barrier against inhaling the virus. A systematic review comparing N95 respirators to standard surgical masks found no significant difference between the two for preventing laboratory-confirmed influenza. Both types reduced risk. If you’re in a high-risk situation, like visiting a hospital or riding public transit during an outbreak, even a basic surgical mask offers protection comparable to a fitted N95 for flu specifically.
Sleep Enough, Especially Around Vaccination
Your immune system does critical work while you sleep, and skimping on rest directly undermines your body’s ability to fight off infections and respond to vaccines. A review published in Current Biology found that sleeping fewer than six hours a night in the days before and after vaccination was linked to a measurably weaker antibody response. Studies using wearable activity trackers to objectively measure sleep found the effect was even more pronounced than self-reported data suggested.
This means the week surrounding your flu shot is an especially important time to prioritize sleep. Aim for seven hours or more. Beyond vaccination, consistent sleep of at least seven hours helps your immune system mount a faster response if you do encounter the virus.
Vitamin D May Offer Additional Protection
A randomized, placebo-controlled trial in schoolchildren found that taking 1,200 IU of vitamin D daily through winter cut influenza A infections nearly in half: 10.8% of children taking vitamin D got the flu compared to 18.6% on placebo. The benefit was even stronger in children who weren’t already taking vitamin D supplements, where the risk dropped by 64%.
This doesn’t mean vitamin D replaces vaccination, but it suggests that maintaining adequate levels through the winter months, when sun exposure drops and deficiency becomes common, gives your immune system a meaningful edge. Many adults are low in vitamin D during flu season without realizing it. A daily supplement of 1,000 to 2,000 IU is a reasonable and safe range for most adults.
Avoid Close Contact During Peak Spread
Flu is most contagious in the first three to four days after symptoms appear, though people can spread it a day before they feel sick. During active outbreaks, limiting time in crowded, poorly ventilated indoor spaces reduces your exposure. If someone in your household is sick, simple measures like sleeping in a separate room, not sharing utensils, and opening windows for ventilation make a real difference.
For people at very high risk of complications, antiviral medications can be prescribed as a preventive measure after a known exposure to influenza. This option is typically reserved for situations like a confirmed flu case in your household when you’re immunocompromised, elderly, or otherwise vulnerable. The medication is taken for 5 to 10 days depending on whether the exposure is ongoing. It’s not a substitute for vaccination but serves as an emergency backup layer of protection.