Myth: You can boost your immune response by not washing your hands.

The concept that not washing your hands will help you build up your immune system was introduced in the late 1980s by a professor who suggested that not exposing yourself to bacteria could compromise your immune system, making you susceptible to illness.

The theory suggested that exposure to small amounts of bacteria "trains" your immune system to fight germs. This training would then strengthen your immune system, making it better able to respond when more germs invade your body.

The reality is different. “Washing your hands is vital to keeping yourself healthy and avoiding the spread of illness,” says Northwestern Medicine Infectious Disease Physician Luis A. Manrique, MD. The flu virus can live on a door handle for 24 hours.

Washing your hands can prevent one in three diarrhea-related sicknesses and one in five respiratory infections. This 20-second routine can single-handedly help you in the battle against germs, including coronavirus, the virus that causes COVID-19, and rhinovirus, the virus that causes the common cold.

A good rule of thumb is to wash your hands with warm, soapy water:

• Before and after eating or handling food
• After using the restroom
• After blowing your nose
• After changing a diaper
• Before and after caring for someone who is sick
• After touching an animal

The U.S. Centers for Disease Control and Prevention (CDC) suggests washing your hands for 20 seconds. That's about the time it takes to sing "Happy Birthday" twice. Dry hands completely afterward to remove any lingering germs.

If soap and water are not available, you can also use a hand sanitizer. Make sure to buy a product that contains at least 60% alcohol.

And, of course, if you really want to boost your immune system, stay up to date on your vaccinations, including your flu shot.