Longitudinal Follow-Up Study on the Side Effects of COVID-19 Vaccines: A Telephonic Questionnaire Approach

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has prompted urgent efforts to develop and deploy effective vaccines. Covishield and Covaxin are two prominent COVID-19 vaccines authorized for emergency use; however, concerns regarding their safety persist.

This longitudinal follow-up study aimed to comprehensively assess and compare the demographic characteristics, frequencies, severities of reported side effects, and associations between vaccine type and demographic factors among individuals vaccinated with Covishield and Covaxin.

A telephonic questionnaire was used to collect data from individuals who attended COVID-19 vaccination programs between January 1, 2021, and January 1, 2022. Logistic regression analysis was performed to investigate the associations between vaccine type, demographic factors, and likelihood of experiencing side effects.

Covaxin recipients exhibited a lower incidence of mild flu-like illness (16 cases) and post-vaccination infection (55 cases) than Covishield recipients (110 and 98 cases, respectively). However, Covaxin recipients reported more cases of soreness at the injection site (139 cases) than did Covishield recipients (172 cases). Logistic regression analysis revealed significantly higher odds of experiencing side effects among Covaxin recipients than among Covishield recipients (OR = 1.687, p < 0.001). Age was inversely associated with the likelihood of experiencing side effects (OR = 0.982, p < 0.001), while sex and ethnicity also exhibited significant associations.

This study provides valuable insights into the safety profiles of the Covishield and Covaxin COVID-19 vaccines. These findings underscore the importance of ongoing surveillance and evaluation of vaccine safety and tolerability to inform public health policies and vaccination strategies.