This year's respiratory virus season in the U.S. is characterized by a simultaneous surge in COVID-19 and influenza, unlike last year when flu and RSV peaked before the omicron wave. Infectious disease expert Dr. Michael Phillips notes that positive tests for both viruses are currently "neck and neck" at NYU Langone Health.

Dr. Helen Chu anticipates a severe flu season in Washington state, as the Pacific Northwest typically experiences a delay compared to other regions. According to the Centers for Disease Control and Prevention (CDC), flu levels are high or very high in at least 38 states, with an estimated 10 million illnesses reported last week. COVID-related hospitalizations have also increased by 20%.

Despite the high circulation of both viruses, coinfections appear to be rare. The CDC found that only 3% of people hospitalized with the flu also tested positive for COVID last year. This trend seems to continue this season, with Dr. Mandy Cohen reporting similar coinfection levels.

Experts attribute this protection from coinfection to the body's immune system. Infection with one virus can enhance the immune response, making it less likely to contract another virus simultaneously. This phenomenon, known as viral interference, is supported by animal studies.

However, individual susceptibility to coinfection varies. Younger individuals may experience temporary resistance to COVID-19 after recovering from the flu, while older or immunocompromised individuals may face more severe consequences. Studies suggest that coinfection with COVID-19 and influenza can increase the risk of severe illness, particularly with the influenza A strain.

While lingering respiratory symptoms are common, they do not necessarily indicate multiple infections. Recovery from respiratory infections can take several weeks. Experts emphasize the importance of staying up to date on COVID-19 and flu vaccines to minimize the impact of these viruses.