Decreased Incidence of Influenza During the COVID-19 Pandemic.

BACKGROUND

The aim of this study was to analyse changes in influenza detection rates of the influenza seasons 2017/2018, 2018/2019, 2019/2020, and 2020/2021 and the changes in personal awareness of protection during the COVID-19 pandemic.

METHODS

This retrospective study included patients tested for influenza virus A and B from November 2017 to March 2021 at the Affiliated People's Hospital of Ningbo University (Ningbo, China). Influenza virus A and B tested by direct RT-PCR. A small group of 100 regular participants in influenza virus detection were surveyed on the use of protective measures in four different influenza seasons.

RESULTS

There were 14,902, 14,762, 25,070, and 1107 tests of influenza virus A and B in the four influenza periods, for total positive rates of 32.45%, 35.77%, 29.40%, and 0.54%, respectively. In the two periods of four influenza seasons, from November to January, the total number of influenza samples was 8530, 4980, 22,925, 868; from February to March, the number of tests was 6372, 9782, 2145, 239. Total number of tests and positive rate decreased significantly from February/March onwards of the 2019/2020 season, coinciding with the beginning of COVID-19. The proportion of people taking protective measures also increased during the 2019/20 and 2020/21 flu seasons.

CONCLUSION

The influenza virus has a high incidence in this area. The diagnosis rate of influenza decreased after the start of the COVID-19 pandemic. The COVID-19 pandemic had an important impact on the detection rates for influenza virus.