A new report from the Centers for Disease Control (CDC) says the flu was measured at “historically low” levels though summer of 2020 as the Covid-19 pandemic was gripping the nation and world.
Below is the CDC’s summary:
What is already known about this topic?
Nonpharmaceutical interventions introduced to mitigate the impact of COVID-19 reduced transmission of common respira- tory viruses in the United States.
What is added by this report?
Influenza viruses and human metapneumovirus circulated at historic lows through May 2021. In April 2021, respiratory syncytial virus activity increased. Common human coronavi- ruses, parainfluenza viruses, and respiratory adenoviruses have been increasing since January or February 2021. Rhinoviruses and enteroviruses began to increase in June 2020.
What are the implications for public health practice?
Clinicians should be aware of increased circulation, sometimes off season, of some respiratory viruses and consider multipatho- gen testing. In addition to recommended preventive actions, fall influenza vaccination campaigns are important as schools and workplaces resume in-person activities with relaxed COVID-19 mitigation practices.
In the United States, influenza activity decreased in March 2020, was historically low through the summer of 2020 (2), and remained low during October 2020–May 2021 (<0.4% of respiratory specimens with positive test results for each week of the season). Circulation of other respiratory patho- gens, including respiratory syncytial virus (RSV), common human coronaviruses (HCoVs) types OC43, NL63, 229E, and HKU1, and parainfluenza viruses (PIVs) types 1–4 also decreased in early 2020 and did not increase until spring 2021. Human metapneumovirus (HMPV) circulation decreased in March 2020 and remained low through May 2021. Respiratory adenovirus (RAdV) circulated at lower levels throughout 2020 and as of early May 2021. Rhinovirus and enterovirus (RV/EV) circulation decreased in March 2020, remained low until May 2020, and then increased to near prepandemic seasonal levels.
Centers for Disease Control
