Most upper respiratory infections spread through tiny airborne particles that float in indoor air, not just through the large droplets from coughs and sneezes that people traditionally worried about. This means prevention goes beyond hand hygiene. A combination of habits, from how you sleep to how you manage indoor air, can meaningfully lower your chances of catching a cold, flu, or other respiratory virus.
How Respiratory Viruses Actually Spread
For decades, the standard advice focused on large droplets and contaminated surfaces. While those routes matter, research now shows that many common respiratory viruses, including influenza, rhinovirus, RSV, and coronaviruses, travel through small aerosols that linger in the air for seconds to hours. These particles float and accumulate in poorly ventilated spaces, which is why indoor environments are far riskier than outdoor ones and why superspreading events happen in crowded, stuffy rooms.
Large droplets fall to the ground within a few meters of an infected person. Aerosols, on the other hand, can travel long distances and build up over time. This distinction matters because it shifts the prevention playbook: surface cleaning helps, but improving the air you breathe is just as important.
Hand Hygiene Still Matters
Washing your hands with soap and water for at least 20 seconds remains one of the simplest defenses. You touch your face dozens of times per hour, and each touch is a chance to transfer a virus from a contaminated surface to your nose, mouth, or eyes. Both soap and water and alcohol-based hand sanitizers reduce germ counts by roughly 92 to 94 percent, with no statistically significant difference between the two. Use whichever one is available, and prioritize it before eating, after being in public spaces, and after blowing your nose.
Improve the Air in Your Home
Because respiratory viruses accumulate in stagnant indoor air, ventilation is a powerful and underused tool. Opening windows, even partially, increases air exchange and dilutes viral particles. When outdoor conditions make that impractical, a portable HEPA air cleaner sized for your room can filter particles in the 0.1 to 1 micrometer range, which includes most respiratory viruses. The EPA recommends choosing a unit rated for your room’s square footage with a high Clean Air Delivery Rate for smoke-sized particles, as those most closely match the size of viral aerosols.
Indoor humidity also plays a role. An MIT study published in the Journal of the Royal Society Interface found that maintaining indoor relative humidity between 40 and 60 percent was associated with lower rates of COVID-19 infections and deaths compared to air that was drier or more humid. Conditions outside that range appear to help viruses survive longer in the air and may impair the protective mucus lining in your airways. A simple hygrometer (under $15 at most hardware stores) lets you monitor this, and a humidifier or dehumidifier can keep you in the sweet spot.
Sleep Is a Front-Line Defense
Your immune system does critical repair and surveillance work while you sleep, and cutting that short has measurable consequences. In a study that deliberately exposed participants to a cold virus, people who slept six hours or fewer per night were nearly twice as likely to develop a clinical cold compared to those who slept eight hours or more. For people who also reported high levels of financial stress, the risk jumped even higher, to about 2.5 times.
This isn’t a vague “get more rest” recommendation. The data points to a specific threshold: consistently sleeping under six hours meaningfully weakens your body’s ability to fight off a respiratory virus once exposed. If you’re in a season when colds and flu are circulating heavily, protecting your sleep is one of the most effective things you can do.
Vitamins and Minerals Worth Considering
Vitamin D has the strongest evidence among supplements for respiratory infection prevention. People with low blood levels of vitamin D get more frequent respiratory infections, and supplementation can close that gap. A large meta-analysis of randomized controlled trials found that taking 400 to 1,200 IU of vitamin D daily reduced the risk of acute respiratory infections by about 8 percent. The benefit was specific to daily dosing (not large weekly or monthly boluses) and was most pronounced during spring, autumn, and winter, when sun exposure drops and vitamin D levels naturally dip.
Zinc gets attention every cold season, but the evidence for prevention is less clear-cut. Starting zinc lozenges within 24 hours of cold symptoms may shorten the illness, but as a daily preventive supplement, the ideal dose and duration haven’t been established. The upper safe limit for adults is 40 mg per day, and long-term use above that can cause copper deficiency and other problems.
Masks in High-Risk Settings
Outside of pandemic mandates, most people won’t wear a mask daily. But during flu season or when you’re in a crowded, poorly ventilated space (a packed subway car, a hospital waiting room, a long flight), a well-fitting mask can make a real difference. A systematic review comparing mask types found that N95 respirators reduced the odds of coronavirus infection by about 70 percent compared to no mask. Standard surgical masks showed a smaller, less statistically reliable benefit, reducing odds by roughly 28 percent for coronaviruses. For influenza specifically, the differences between mask types were less pronounced and not statistically significant in the studies reviewed.
The fit matters as much as the filter. A loosely worn N95 performs closer to a surgical mask. If you’re going to mask up in a high-risk situation, press the nose wire snugly and make sure there are no gaps at the cheeks or chin.
Stay Current on Vaccines
Vaccination remains the most direct way to prevent the respiratory infections that cause the most severe illness. The CDC’s 2025 adult immunization schedule recommends an annual flu shot for all adults 19 and older, with higher-potency formulations preferred for those 50 and up. COVID-19 vaccination is recommended with an emphasis on people at increased risk of severe disease, though all adults are eligible for an updated dose. RSV vaccination is recommended for adults 75 and older, adults 60 to 74 with risk factors for severe RSV, and pregnant individuals between 32 and 36 weeks of gestation during RSV season (September through January in most of the continental U.S.).
None of these vaccines guarantee you won’t get infected, but they significantly reduce the chance of a mild upper respiratory infection turning into pneumonia or a hospital stay.
Nasal Saline Irrigation
Rinsing your nasal passages with saline solution is a low-cost, low-risk habit that may help. In a randomized trial of 60 adults, those who performed daily saline nasal irrigation reported significantly fewer infections, shorter symptom duration, and fewer days with nasal congestion compared to those who didn’t irrigate. A larger trial in 390 children found similar benefits for both treatment and prevention phases, with improved nasal clearance and less need for medication.
The evidence is still limited, but the downside is essentially zero. Using a neti pot or saline squeeze bottle with distilled or previously boiled water once daily during cold and flu season is a reasonable addition to your routine.
Putting It All Together
No single strategy prevents every upper respiratory infection. The people who get sick least often tend to layer several habits: they sleep enough, wash their hands consistently, keep their indoor air clean and properly humidified, stay up to date on vaccines, and reach for a mask when the situation calls for it. Most of these adjustments cost little or nothing and become automatic once established. The goal isn’t to live in a bubble. It’s to tip the odds in your favor during the months when respiratory viruses are everywhere.