The cold and flu season is currently in full effect as four significant respiratory viruses spread across the nation. The Centers for Disease Control and Prevention (CDC) reports that at least 15 states are experiencing “very high” flu activity.

According to the CDC’s wastewater monitoring systems, influenza levels in wastewater have surged across the country for the week ending January 4.

Winter months tend to facilitate the rapid spread of respiratory viruses as people gather indoors more frequently. Experts note that colder weather can impair the immune system, and the dry, chilly air can create a favorable environment for these viruses to flourish.

Wastewater surveillance reveals high levels of flu, COVID, and RSV

Testing wastewater serves as an important early warning tool for public health officials, helping them to manage and prevent potential outbreaks.

Even if people in a community aren’t displaying symptoms, it is still possible to analyze wastewater for traces of infectious diseases. The CDC’s data can highlight fluctuations in illness levels within your state.

Are you dealing with flu, COVID, a cold, or something else?

Respiratory viruses, such as the common cold, share symptoms with COVID-19 and the flu, making it challenging to identify the exact cause of a cough, sneeze, or fever without a test.

The Mayo Clinic indicates that COVID-19 symptoms may manifest later than those of a cold or the flu. While a fever is uncommon with a cold, muscle aches and fatigue are not typically present either.

Headaches often occur with both flu and COVID-19, but they aren’t usually associated with colds. Additionally, a dry cough is more prevalent with COVID-19 than with the flu.

Here are some indicators to help distinguish between the symptoms of respiratory viruses:

Flu hospitalizations are increasing

In the 2023-2024 flu season, there have been approximately 470,000 hospitalizations and 28,000 fatalities attributed to the flu. To date, there have been over 5.3 million reported cases, 63,000 hospitalizations, and 2,700 deaths.

This article has been updated with new information.