OBJECTIVES: We aimed to study the effect of seasonal influenza (flu) vaccination on the susceptibility to coronavirus disease 2019 (COVID-19). METHODS: A total of 203 healthcare workers of a pandemic centre of Istanbul, Turkey, were included in this retrospective study. According to the presence or absence of flu vaccination, participants were divided into group 1 and group 2. A comparison of the rate of COVID-19 was done between these two groups. Also, the mean age and the sex ratio of females/males were evaluated and compared between these two groups. RESULTS: Group 1 participants (n = 65) were older than participants in group 2 (n = 138) (p < 0.05). Despite of this, interestingly, the COVID-19 infection rate was lower in the 1st group (in comparison to the 2nd group) (p < 0.05). CONCLUSION: Our study results showed that, even if low, the flu vaccination may have a protective effect on the susceptibility to COVID-19 infection. Using this beneficial adjuvant effect of the vaccine may help us in this unpredictable battle with the COVID-19 pandemic. Further studies are needed to confirm this assumption.

Hamidiye Health Services College University of Health Sciences Istanbul Turkey

Infectious Diseases Department Bagcilar Training and Research Hospital University of Health Sciences Istanbul Turkey

Infectious Diseases Department Bakirkoy Dr Sadi Konuk Training and Research Hospital University of Health Sciences Istanbul Turkey

Internal Medicine Department Bakirkoy Dr Sadi Konuk Training and Research Hospital University of Health Sciences Istanbul Turkey

Internal Medicine Department Basaksehir Cam and Sakura Sehir Hospital University of Health Sciences Istanbul Turkey

Public Health Department Istanbul Medical Faculty Istanbul University Istanbul Turkey

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