Evaluation of the Possible Effect of the Influenza Vaccine on the Severity, Mortality, and Length of Hospitalization among Unvaccinated COVID-19 Patients; An Observational, Cross-Sectional Study
Background: Based upon WHO (World Health Organization) Coronavirus Dashboard more than 5 million deaths worldwide have been attributed to the COVID-19 (Coronavirus Disease 2019) caused by the SARS-Cov-2 virus (Severe Acute Respiratory Syndrome Coronavirus) till November 2021. The annual flu vaccination has raised many questions about the vaccine's effects on Covid-19 outcomes. Several possible mechanisms including cross-reactivity and cross-protection have been reported to be responsible for the potential protective effect of the flu vaccine on the COVID-19 infection. This study was performed to evaluate the possible effect of the influenza vaccine on the disease severity, the mortality rate, and the length of hospitalization in COVID-19 patients. Methods: The data of 1300 patients were recorded from May 2020 to October 2020. Patients with a previous history of COVID-19, patients under 18 years old, and patients who did not have accurate information about their influenza vaccination history were excluded. 498 hospitalized unvaccinated COVID-19 patients with typical clinical manifestations and a positive PCR (Polymerase Chain Reaction) test for COVID-19 were included in this observational, cross-sectional study. The participants were divided into two groups (vaccinated and unvaccinated) based on the history of influenza vaccination at the time of admission.Results: The length of hospital stay was lower in the vaccinated compared to the unvaccinated group (p < 0.05). However, there was no significant difference between the mortality rate, the need for ICU (Intensive Care Unit) admission, and the severity of the disease between the two groups (p> 0.05).Conclusion: Since the patients studied in this article did not receive any of the Covid-19 vaccines; Therefore, the effect of influenza vaccination on the clinical course of Covid-19 can be evaluated using the results of this study. A longer length of hospital stay was observed in the unvaccinated patients in our study, which may suggest the possible protective effect of the influenza vaccine against COVID-19.
2. 8 Things to know about pandemic influenza: World Health Organization; 2021 [Available from: https://www.who.int/news-room/feature-stories/detail/8-things-to-know-about-pandemic-influenza.
3. Khodamoradi Z, Moghadami M, Lotfi M. Co-infection of Coronavirus Disease 2019 and Influenza A: A Report from Iran. Arch Iran Med 2020;23(4):239-43.
4. Ozaras R, Cirpin R, Duran A, Duman H, et al. Influenza and COVID-19 coinfection: Report of six cases and review of the literature. J Med Virol 2020;92(11):2657-65.
5. Bai L, Zhao Y, Dong J, et al. Coinfection with influenza A virus enhances SARS-CoV-2 infectivity. Cell Res 2021;31(4):395-403.
6. Massoudi N, Mohit B. A Case-Control Study of the 2019 Influenza Vaccine and Incidence of COVID-19 Among Healthcare Workers. J Clin Immunol 2021;41(2):324-34.
7. Noale M, Trevisan C, Maggi S, et al. The Association between Influenza and Pneumococcal Vaccinations and SARS-Cov-2 Infection: Data from the EPICOVID19 Web-Based Survey. Vaccines (Basel) 2020;8(3):471.
8. Conlon A, Ashur C, Washer L, Eagle KA, Hofmann Bowman MA. Impact of the influenza vaccine on COVID-19 infection rates and severity. Am J Infect Control 2021;49(6):694-700.
9. Candelli M, Pignataro G, Torelli E, et al. Effect of influenza vaccine on COVID-19 mortality: a retrospective study. Intern Emerg Med 2021;16(7): 1849-1855.
10. Wilcox CR, Islam N, Dambha-Miller H. Association between influenza vaccination and hospitalisation or all-cause mortality in people with COVID-19: a retrospective cohort study. BMJ Open Respir Res 2021;8(1):e000857.
11. Fink G, Orlova-Fink N, Schindler T, et al. Inactivated trivalent influenza vaccination is associated with lower mortality among patients with COVID-19 in Brazil. BMJ Evid Based Med 2020:bmjebm-2020-111549.
12. Amato M, Werba JP, Frigerio B, et al. Relationship between influenza vaccination coverage rate and COVID-19 outbreak: An Italian ecological study. Vaccines 2020;8(3):535.
13. Zanettini C, Omar M, Dinalankara W, et al. Influenza Vaccination and COVID19 Mortality in the USA (preprint). MedRxiv. 2020.
14. Cowling BJ, Fang VJ, Nishiura H, et al. Increased risk of noninfluenza respiratory virus infections associated with receipt of inactivated influenza vaccine. Clin Infect Dis 2012;54(12):1778-83.
15. Sundaram ME, McClure DL, VanWormer JJ, Friedrich TC, Meece JK, Belongia EA. Influenza Vaccination Is Not Associated With Detection of Noninfluenza Respiratory Viruses in Seasonal Studies of Influenza Vaccine Effectiveness. Clin Infect Dis 2013;57(6):789-93.
16. Cox MJ, Loman N, Bogaert D, O'Grady J. Co-infections: potentially lethal and unexplored in COVID-19. Lancet Microbe 2020;1(1):e11.
17. Iacobucci G. Covid-19: Risk of death more than doubled in people who also had flu, English data show. BMJ 2020;370:m3720.
18. Stowe J, Tessier E, Zhao H, et al. Interactions between SARS-CoV-2 and Influenza and the impact of coinfection on disease severity: A test negative design. medRxiv 2020:2020.09.18.20189647.
19. Arokiaraj MC. Considering Interim Interventions to Control COVID-19 Associated Morbidity and Mortality-Perspectives. Front Public Health 2020;8:444.
20. Leentjens J, Kox M, Stokman R, et al. BCG Vaccination Enhances the Immunogenicity of Subsequent Influenza Vaccination in Healthy Volunteers: A Randomized, Placebo-Controlled Pilot Study. J Infect Dis 2015;212(12):1930-8.
21. Mohanty S, Joshi SR, Ueda I, et al. Prolonged proinflammatory cytokine production in monocytes modulated by interleukin 10 after influenza vaccination in older adults. J Infect Dis 2015;211(7):1174-84.
|Issue||Vol 10, No 1 (Winter 2022)|
|COVID-19 Influenza Vaccine Prognosis|
|Rights and permissions|
|This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.|