Most U.S. states are reporting high or very high flu-like activity, while COVID-19 rates remain lower than this time last year.

There’s no medication for norovirus. Instead, you’ll need to rehydrate as much as possible with water and other liquids. Seek help if you are dehydrated and notice you have a dry mouth and throat, aren’t urinating as much or feel dizzy when you’re standing up.

Influenza A, COVID-19 and norovirus (stomach flu) are on the rise, according to the Centers for Disease Control and Prevention. But there's a fourth "bug" the public should be aware of: respiratory syncytial virus. RSV causes cold-like symptoms and affects the breathing passages and lungs.

This fall saw an unusually high number of cases of “walking” or mycoplasma pneumonia, a mild pneumonia that typically causes a severe cough but less fatigue than more serious forms of the disease.

If it feels like everyone around you is fighting off a cold or recovering from the flu, it may be because respiratory illnesses are running rampant in most of the United States, and cases are only increasing.

The flu, norovirus, COVID and RSV are all at elevated levels — and officials at the CDC expect it to stay that way for weeks. NBC medical contributor Dr. Natalie Azar joins TODAY with tips for keeping you and your family healthy and what to know about vaccines.