COVID-19 and Seasonal Influenza: No Room for Two.

Nikolaos Spantideas,Neha Khanderia,Eirini G Drosou,Summina Rai,Anastasia M Bougea

doi:10.7759/cureus.18007

Abstract

ObjectiveWith the outbreak of COVID-19 in December 2019 fears were expressed for a possible twindemic in the coming flu seasons. Fortunately, this was not the case for the 2019-2020 and 2020-2021 flu seasons as flu showed very low historical rates during these periods. The objective of our study was to look at the existing flu data for the 2019-2021 period and analyze possible reasons for the near absence of seasonal flu.MethodsWe performed retrospective surveillance regarding seasonal influenza rates for the years 2019-2021, the years that the COVID-19 was present. Epidemiological data concerning seasonal influenza for the years 2019-2021 were collected and analyzedResultsExtremely low numbers of flu cases were reported in FluNet, FluView, and TESSy influenza surveillance systems during the years 2019, 2020, and 2021 compared to previous years prior to COVID-19.ConclusionsA twindemic outbreak during the 2019-2021 flu seasons did not occur despite expressed concerns. The worldwide implementation of mitigation measures for individuals and communities to control severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission, the increased flu vaccination rate, the virus interference and the lower rate of testing for flu are the main reasons for the marked decrease in reported flu cases during 2019-2021 flu seasons.

Highlights

Seasonal influenza is a worldwide contagious upper and lower respiratory tract illness caused predominantly by type A and B influenza viruses
Low numbers of flu cases were reported in FluNet, FluView, and TESSy influenza surveillance systems during the years 2019, 2020, and 2021 compared to previous years prior to COVID-19
A twindemic outbreak during the 2019-2021 flu seasons did not occur despite expressed concerns

Summary

Introduction

Seasonal influenza is a worldwide contagious upper and lower respiratory tract illness caused predominantly by type A and B influenza viruses. Influenza epidemics have a seasonality generally occurring in regular annual epidemics in autumn and winter. Influenza epidemics usually occur annually and influenza pandemics every 10-15 years. Type A viruses are responsible for the highest burden of disease during seasonal epidemics and type B infections are less common and usually milder than influenza A. The World Health Organization (WHO) estimates that globally seasonal influenza epidemics cause an annual three to five million severe cases and 290,000 to 650,000 deaths. Young children, the elderly, and people with chronic illnesses are at high risk for severe illness and death associated with influenza virus infection [2]. The economic and health care burden of influenza epidemics is substantial despite the short duration of the illness [3]

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Discussion

Conclusion