A bright spot: Extremely low prevalence of influenza in the U.S. this flu season

The message rang out loud and clear last fall: "Get your flu shot." With the pandemic raging, health care providers were concerned that a wave of seasonal influenza on top of growing COVID-19 cases would push the rates of illness and death higher while depleting vital health care resources.

Matthew Binnicker, Ph.D.

That message, coupled with strategies to prevent COVID-19, appears to have done its work. According to Matthew Binnicker, Ph.D., director of the Clinical Virology Laboratory at Mayo Clinic in Rochester, Minnesota, the rate of illness tied to influenza in the U.S. now is extremely low.

"This year, we've seen minimal, if any, influenza activity in many states throughout the country," Dr. Binnicker says. "Here in Minnesota, we're just not seeing influenza at this point, which is quite atypical. We have had past seasons where we haven't seen many cases until mid-to-late January, but that is not common. In most seasons, we are approaching peak influenza at this time of year."

Due to the risk of influenza and COVID-19 circulating at the same time, practice leadership at Mayo Clinic implemented broad testing for both viruses at the traditional start of the flu season. Beginning Dec. 1, 2020, all patients showing respiratory symptoms have been tested for COVID-19 and influenza. To date, almost 20,000 influenza tests have been conducted at Mayo Clinic in Rochester — a testing rate much higher than usual. The number of positive influenza cases so far is zero.

Dr. Binnicker points to several reasons for that. "The emphasis on getting the flu shot definitely is a component, but I don't think that's the complete explanation for why we haven't seen much influenza," he says. "The second component is all the mitigation factors we've been practicing over the last 10 months. We know that influenza and COVID spread through similar pathways. Disrupting the transmission pathway by wearing masks in public, limiting large gatherings, and social distancing, breaks the transmission cycle for these viruses. Both of those measures — the flu vaccine and the infection prevention strategies — are significant here."

In a typical year, there are between 10,000 and 30,000 deaths in the U.S. associated with influenza infection. Of those, approximately 150 to 200 are children. So far this season, there has been one pediatric death related to influenza in the entire country.

"In many ways, we've become accustomed to the typical number of deaths we see each year from influenza," Dr. Binnicker says. "But our experience with this pandemic has taught us that if we follow precautionary measures, we can dramatically change that picture and save lives."

Dr. Binnicker emphasizes that, after the pandemic is over, he's not a proponent of year-round universal masking or shutting down large public gatherings. But the infection prevention measures proven to slow the spread of COVID-19 and influenza should be continued in some form in the future.

"We need to commit ourselves to doing simple things like staying home when we're sick and wearing a mask in public places when we're seeing a surge in serious respiratory illness," he says. "When we practice these prevention measures, this year's influenza numbers show that we can really reduce the risk of severe illness and decrease the number of deaths in our communities."

Source: Minnesota Department of Health Weekly Influenza & Respiratory Activity Report for Week Ending January 2, 2021

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Tracy Will

Tracy Will is a senior marketing specialist at Mayo Clinic Laboratories where she covers innovation, specialty testing, and advances in laboratory medicine. Tracy has worked at Mayo Clinic since 2016.