Flu Season Questions, Answered

Seasonal flu peaks in the Northern Hemisphere in winter, usually between December and February, though the season can start as early as October and run into spring. Most people recover in a week or two, but flu causes hundreds of thousands of hospitalizations in the US in a typical year, mostly among older adults, young children and people with chronic health conditions. These are the questions people most often ask.

Who should get a flu vaccine?

The US Centers for Disease Control and Prevention recommends an annual flu vaccine for almost everyone aged six months and older, with rare exceptions. It matters most for adults 65 and older, pregnant people, young children and anyone with conditions such as asthma, diabetes or heart disease. Getting vaccinated also lowers the chance of passing flu to people who are more vulnerable.

When is the best time to get it?

September and October are generally considered ideal, so protection is in place before flu spreads widely. The body takes about two weeks after the shot to build protection. Getting vaccinated later is still worthwhile, since flu often circulates into spring.

Why every year?

Flu viruses change constantly, and the vaccine is updated each year to match the strains expected to circulate. Protection from a vaccine also fades over the months after it is given.

Can the vaccine give me the flu?

No. Flu shots contain inactivated virus or a single protein from it, which cannot cause infection. A sore arm, mild aches or a low fever for a day or so are common and are signs of the immune system responding.

What else lowers the risk?

Wash hands with soap and water for at least 20 seconds, especially before eating and after being out in public, or use a hand sanitizer with at least 60 percent alcohol. Avoid touching your eyes, nose and mouth. Clean frequently touched surfaces at home when someone is sick. In crowded indoor places during a bad season, a well-fitting mask reduces exposure. Good sleep, regular activity and not smoking all support the immune system generally.

How do I tell flu from a cold?

Flu usually starts suddenly, with fever or chills, body aches, exhaustion, headache and a dry cough. A cold comes on more gradually and mostly affects the nose and throat. COVID-19 can look like either, so a home test can help sort it out.

What if I get sick?

Rest, drink fluids and stay home. Current CDC guidance for respiratory illnesses is to stay home and away from others until your symptoms have been improving overall and you have had no fever for at least 24 hours without fever-reducing medicine, then take extra precautions such as masking for a few days after.

Prescription antiviral medicines, such as oseltamivir, can shorten illness and reduce the risk of complications. They work best when started within about two days of symptoms beginning, so people at higher risk should contact a doctor early rather than waiting to see if it passes.

When is it an emergency?

Seek urgent care for difficulty breathing, chest pain or pressure, confusion, severe weakness, seizures, bluish lips, signs of dehydration, or symptoms that improve and then return with fever and a worse cough. In children, watch also for fast breathing, ribs pulling in with each breath, not waking or interacting, and no tears when crying.