According to the CDC, Influenza activity has fallen to and remained at historically low interseasonal levels. After recognition of widespread transmission of SARS-COV-2, the virus that causes COVID-19, the percentage of U.S. respiratory specimens submitted for influenza testing that tested positive decreased from 20% to 2.3% in Northern Hemisphere countries. Data from Southern Hemisphere countries also indicate little Influenza activity.
These sharp decreases in influenza cases amidst the COVID-19 pandemic can be attributed to multiple factors including changes in the frequency of patient health seeking for respiratory illness as well as changes in influenza virus circulation because of widespread implementation of measures to mitigate of SARS-COV-2. Data from clinical laboratories in the United States indicated a 61% decrease in the number of specimens submitted (from a median of 49,696 per week during September 29, 2019–February 29, 2020, to 19,537 during March 1–May 16, 2020) and a 98% decrease in influenza activity as measured by percentage of submitted specimens testing positive (from a median of 19.34% to 0.33%). Interseasonal (i.e., summer) circulation of influenza in the United States (May 17–August 8, 2020) is currently at historical lows (0.20% tests positive in 2020 versus 2.35% in 2019, 1.04% in 2018, and 2.36% in 2017). Influenza data reported to the World Health Organization’s (WHO’s) FluNet platform from three Southern Hemisphere countries showed very low influenza activity during June–August 2020, the months that constitute the typical Southern Hemisphere influenza season.
Based on this data it is likely that in communities where extensive COVID-19 mitigation measures are maintained (e.g., face masks, social distancing, school closures, and teleworking), those areas might have little influenza circulation during the upcoming 2020-2021 Northern Hemisphere influenza season. The CDC states that 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. 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. Influenza vaccination of all persons 6 months and older remains the best method for influenza prevention and mitigation and is especially important this season when SARS-COV-2 (COVID-19) and influenza virus might cocirculate.
Although this data is compelling in proving a lower transmission rate of influenza amidst the COVID-19 pandemic, it is important to note that many different factors could have played a part in the results of these studies including sharp reductions in global travel, in-person social contact, or increased vaccine use. Another explanation for lower influenza cases and transmission could be viral interference caused by another respiratory virus that might outcompete influenza in the respiratory tract. Since the data does not definitively suggest that influenza isn’t still a threat and could possibly cocirculate if COVID restrictions relax, the CDC still recommends influenza vaccination for the 2020-2021 flu season.
It is important for all healthcare providers to note these changes in influenza and COVID-19 transmission as we learn to tackle this unprecedented flu-season heading into the new year. Given the continued threat of COVID-19 it is especially important for healthcare providers to take every precaution they can for their patients and community, which is why influenza vaccination paired with other mitigation efforts in the midst of the pandemic is crucial.
As always AMSCO medical is here to help you deliver the highest quality care to your patients during upcoming busy season.
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