What is the contagious period for the flu?

Infectious Diseases Uncategorized

People with flu are most contagious in the three to five days after they first feel sick. This is a bit later than COVID-19, which often spreads a day or two before symptoms.

You might infect someone as early as a day before or as late as a week after becoming sick, but this is less likely. Some people may be contagious even longer – such as young children or people with weakened immune systems.

Those Nerdy Girls recommend dialing up your precautions for the first five days to play it safe, even if you’re not sure which nasty bug you have. We know this isn’t always realistic, especially for parents of young children who need snuggles. We’ve been there! Just do the best you can. Getting your flu shot stacks the odds in your favour. It’s also worth layering other precautions, like limiting close contact, masking, and frequent hand-washing.

Beyond five days of symptoms, the risk of spreading flu (influenza virus) is low, but not zero. If you’re spending time with people who are vulnerable to severe flu outcomes, it’s worth playing it safe for a full week. The phrase “just the flu” does a disservice to the toll of this illness. Flu can be devastating for babies, toddlers, older adults, and people with other health conditions (see link below on vulnerable populations).

Fun fact: You’ll have to wait a few days to know whether or not the flu (influenza virus) has spread. The amount of time from flu exposure to symptoms is usually about two days, but can range from one to four days.


With flu, most people are contagious when they have symptoms. This means that staying home when sick, even if you don’t know what virus you have, is very effective in preventing further spread.

Stay safe. Stay well.

Those Nerdy Girls