Lauren Dempsey, MS in Biomedicine and Law, RN, FISM News
During the 2020-2021 flu season the United States and the world saw abnormally low numbers of flu cases. Most experts agree that school and business closures as well as other pandemic mitigation strategies such as handwashing, mask wearing, and social distancing were all factors that led to reduced transmission of the virus and a much milder flu season.
According to the CDC, in the United States 0.2% of the respiratory specimens tested in laboratories were positive for an influenza virus last year, which was shockingly low when compared to previous seasons. Typically, positive test results for the flu are between 26% and 30%.
However, because there was such a reduction in positive cases last season, it may mean that this year we are facing a worse-than-normal flu season. Clare Rock, a physician at Johns Hopkins University School of Medicine said “there is thought we may be facing a more severe flu season because we didn’t have as much flu last year, and “that means some of the natural immunity that would be in the population is not going to be in the population now. We may have more vulnerable people.”
Medical experts and the CDC have urged Americans to continue to follow COVID-19 mitigation strategies and to get vaccinated for the flu and COVID-19, especially since the viruses share similar symptoms. The CDC recommends that it is important to get tested to determine what the illness is and to ensure patients receive proper treatment, despite the fact that there is currently no outpatient treatment options for the coronavirus.
The CDC tracks the overall burden of influenza for each season. It says that in “the 2019-2020 season there was an estimated 35 million flu-related illnesses, 16 million flu-related medical visits, 380,000 flu-related hospitalizations, and 20,000 flu-related deaths.” Two analyses from the University of Pittsburgh Graduate School of Public Health were recently published detailing the potential for a “more severe than average flu season”, but that could be lessened if flu shot rates increased by 20% to 50%.
Dr. Mark Roberts, director of the Public Health Dynamics Laboratory at the University of Pittsburgh Graduate School of Public Health, and senior author of both studies said “vaccinating as many people against the flu as possible will be key to avoiding this scenario,” and that there has recently been an increase in other respiratory infections such as respiratory syncytial virus, which indicates that this “does not bode well for the coming flu season.”
In February 2021 the WHO made recommendations on which flu strains should be considered for vaccine production. This was based on circulating strains and there are currently vaccines available for influenza A and influenza B which come in trivalent and quadrivalent vaccines, meaning that they protect against multiple strains.
Vaccine efficacy varies from year to year based on the active strand circulating. In the 2019-2020 flu season the vaccine was 39% effective, but some years it has been much lower. During the 2004-2005 flu season the vaccine was only 10% effective.
With the expectation that this could be a particularly bad flu season, there is a potential for a “’twindemic’ — a coinciding flu and COVID-19 epidemic” according to Roberts. He added that “if anything, our models show that we should be more concerned this year about the possibility of a surge in COVID-19 hitting at the same time as a massive flu outbreak in areas of the country with low vaccination rates against both diseases.”
However, there are still many unknown factors that are at play which will determine the nature of this flu season. One is the questions that continue to swirl on the efficacy of the COVID-19 vaccination along with the unknown efficacy of this year’s flu shot. Another factor is that the strict prevention measures that many areas are still using to combat COVID-19 would likely lower the transmission of the flu as well.