By Jonathan Springston, Editor, Relias Media

After the implementation of mitigation tactics such as masking and physical distancing to slow the spread of COVID-19, the number of influenza cases began declining, too, according to the results of a recent study.

Investigators observed data from the World Health Organization that indicated low influenza activity between June and August 2020 in the Southern Hemisphere, the typical influenza season for that part of the world. Later, these researchers pulled data from about 300 U.S. clinical labs that participate in virologic surveillance for influenza to determine whether similar trends may hold true for the Northern Hemisphere.

From these data, researchers discovered a 61% decline in the number of specimens submitted (median 49,696 cases per week Sept. 29, 2019 to Feb. 29, 2020, to 19,537 cases per week March 1, 2020 to May 16, 2020). Summer flu circulation in the United States (May 17, 2020 to Aug. 8, 2020) remained low as well (median = 0.20% tests positive in 2020 vs. 2.35% in the same period in 2019, 1.04% in 2018, and 2.36% in 2017).

The authors noted that March 1, 2020, is when the United States declared COVID-19 a national emergency. After that, Americans began working from home, schools closed and switched to online learning, and elected officials urged social distancing measures and for everyone to wear a mask. Although these practices have varied, it appears such measures are slowing the spread of both COVID-19 and the flu.

“In countries or jurisdictions where extensive community mitigation measures are maintained (e.g., face masks, social distancing, school closures, and teleworking), those locations might have little influenza circulation during the upcoming 2020-21 Northern Hemisphere influenza season. The use of community mitigation measures for the COVID-19 pandemic, plus influenza vaccination, are likely to be effective in reducing the incidence and impact of influenza, and some of these mitigation measures could have a role in preventing influenza in future seasons,” the authors concluded. “However, given the novelty of the COVID-19 pandemic and the uncertainty of continued community mitigation measures, it is important to plan for seasonal influenza circulation in the United States this fall and winter.”

In the upcoming November issue of ED Management, experts will provide more input on what epidemiologists are expecting about influenza this year, how COVID-19 pandemic-related mitigation measures may affect flu season severity, and what steps hospitals and EDs are taking to be optimally prepared.