Effect of COVID-19 vaccination on influenza-associated respiratory infection (IARI): benefit or backfire

Undoubtfully, COVID-19 vaccine (C19V) has significantly changed the pandemic's trajectory positively. At the same time, reports of transient local and systemic post-vaccination reactions leave a concern about its unknown impact on common ailments. Its effect on IARI is unclear because the present IARI epidemic began immediately after C19V in the previous season.

A retrospective observational cohort study among 250 Influenza-associated respiratory infection (IARI) patients by a structured interview questionnaire was conducted with the comparison between 3 groups with 1 dose, 2 doses and 2 doses plus booster dose of C19V. The p<0.05 was considered significant in this study.

Among samples 21.2% received one dose of the C19V, only 3.6% got Flu vaccination, 30% had ≥2 comorbidities such as diabetes (22.8%), hypertension (28.4%) and ionically, 77.2% were on chronic medications. Significant differences (p<0.05) were found between groups with duration of illness, cough, headache, fatigue, shortness of breath and hospital visits. The logistic regression analysis shows that the extended IARI symptoms and hospital visits were significantly high among Group 3 (OR=9.17, 95% CI=3.01-29.0) and the same trend remained significant after adjusting the incidence of comorbidities among samples, the chronic conditions (OR=5.13, 95% CI=1.37-14.91) and flu vaccination status (O=4.96, 95% CI=1.41-16.2). Also, 66.4% of the patients were indecisive about getting vaccinated further.

It has been challenging to reach any definitive conclusions regarding the effects of C19V on IARI, conducting extensive, substantial population-based studies that integrate clinical and virological data from more than one season is absolutely required, despite the fact that the majority of the reported effects were mild and temporary.