Significance of Flu Vaccination against SARS-CoV-2 Infection: A Questionnaire-based Survey

Introduction: Before the Coronavirus Disease 2019 (COVID- 19) vaccines were developed, there was an intense search for preventive measures and effective treatments of COVID-19, which has led to a recommendation of influenza vaccination as a preventive measure against COVID-19. As of August 2022, there are still many countries where percentage of at least one dose of COVID-19 vaccination is ≤20%. In such a scenario it becomes pertinent for a continuous search of other preventive measures such as significance of flu vaccination against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection. Aim: To explore any relation between the flu vaccination and SARS-CoV-2 infection. Materials and Methods: A retrospective case control study was undertaken through questionnaire-based survey with 200 cases who had taken flu vaccination within one year of COVID-19 testing and 800 as controls. All candidates were consecutively enrolled in this study and informed consent was obtained. Results: Most common age group among vaccinated candidates was 31-40 years. Among 200 individuals of cases group, 3 (1.5%) were positive for COVID-19 and 197 (98.5%) were negative. Among 3 positive individuals in cases only one required hospitalisation. Among 800 control group, 38 (4.7%) were positive and 762 (95.2%) were negative for SARS-CoV-2 infection. Rate of positivity was 2.3% less among vaccinated group in comparison to non vaccinated group. Conclusion: In this study it was observed that individuals who had received the flu vaccine there was a significant reduction in odds of testing positive for COVID-19 compared to those who did not received the vaccine.