Flu has officially hit a second high in the US: Know the symptoms

This story was updated with new information from the CDC.

U.S. influenza infections are at or near their highest levels in at least 15 years and are still rising, according to the latest data from the U.S. Centers for Disease Control and Prevention.

The cold and flu season is in full swing as respiratory viruses circulate throughout the country. Forty-six states reported "very high" and "high" levels of the flu, according to a CDC report.

So far this season, the flu has contributed to at least 29 million illnesses, 370,000 hospitalizations and 16,000 fatalities, according to the CDC.

What to know about the flu virus in the U.S.

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Wastewater map tracks rise in flu activity

The main objective of wastewater testing is to give public health experts an early warning system so they may contain outbreaks.

Wastewater, or sewage, can be tested for infectious diseases even when the people living in a community are not exhibiting any symptoms. The CDC's data can identify potential shifts in the number of illnesses in your state.

28 states' wastewater testing shows 'very high' flu activity

Know the symptoms of the flu

Doctors and health professionals are recommending that everyone 6 months and older get vaccinated against influenza during the flu season because the symptoms overlap with COVID-19's. Your immune system may be weakened by one infection, leaving you more vulnerable to others.

The flu and COVID-19 have several symptoms in common. Here's how you can tell between the two viruses:

Six habits for staying healthy this flu season

1. Get the flu vaccine; it's not too late.
2. Cover your mouth and nose with a tissue, not your hands, when sneezing or coughing.
3. If you're feeling symptoms developing, don't go to work or school. This will prevent spreading the illness to others.
4. Avoid touching your eyes, nose and mouth. If you touch something that is contaminated with germs, it can easily spread disease.
5. Clean and disinfect your home frequently, especially surfaces that are touched often, such as doorknobs and countertops.
6. Wash your hands frequently with soap and water. Scrub for 20 seconds to remove harmful germs.

CONTRIBUTING Jim Sergent

SOURCE Centers for Disease Control and Prevention, Harvard Health, Mayo Clinic and Reuters