Clinicians should be aware of increasing respiratory virus circulation and consider multipathogen testing, according to the CDC's Morbidity and Mortality Weekly Report published July 23.
Nonpharmaceutical interventions — such as decreased travel, mask use and physical distancing — used to mitigate COVID-19 spread have reduced transmission of common respiratory viruses, with flu viruses and human metapneumovirus hitting historic lows through May 2021.
However, respiratory syncytial virus activity in the U.S. increased in April 2021, while common human coronaviruses, respiratory adenoviruses and parainfluenza viruses have been increasing since January or February 2021. Rhinoviruses and enteroviruses also began to increase in June 2020.
"Among each group of viruses, changes in the circulation of specific species and types warrant further assessment," the report said.
Reduced circulation of flu viruses may affect the severity of the upcoming flu season given the prolonged lack of ongoing natural exposure to flu viruses. Lower levels of immunity, especially among younger children, could prompt more widespread disease and a potentially more severe epidemic, reports the CDC.