BackgroundThere were many studies conducted to determine how immunization affects people with long-term COVID. The results of those studies have caused debate as they gave rise to varying outcomes. Some evidence indicates a change in, an improvement in, a continuation of, or even a worsening of long-term COVID symptoms following vaccination. The ratio of change in antibody titers was noticeably larger in the group of people whose illnesses became worse. Hence, this study aimed to explore potential post-COVID-19 vaccination syndrome (PCVS) in vaccinated individuals and also to assess their quality of life (QoL). MethodologyBetween September 2021 and May 2023, an ambidirectional, descriptive, follow-up cohort study was conducted, enrolling participants who were 18 years of age or older, met the vaccination requirements established by the Ministry of Health and Family Welfare, Government of India, and had completed the primary immunization series with the AZD1222® or BBV152® vaccine. The prevalence of PCVS and the QoL measured using EQ-5D-5L were assessed at 1 month, 6 months, and 12 months post-COVID-19 vaccination. ResultsAZD1222® vaccine was received by 84.28% (343) of the participants, and BBV152® vaccine was received by 15.72% (64) of the study participants. A month after the primary vaccination series, 52.8% (215) of the total participants had at least 1 PCVS, 39.8% (162) at 6 months, and 64.6% (263) at 12 months. Among those who had received vaccinations, the QoL increased at 6 months to 0.975±0.08 and declined at 12 months to 0.94±0.13 from 0.949±0.13 at 1 month after receiving a primary immunization. The overall prevalence of PCVS between AZD1222®-vaccinated individuals and BBV152®-vaccinated individuals at a month post-vaccination was 54.5% vs. 43.8%, at 6 months it was 41.1% vs. 32.8%, and at 12 months it was 65.59% vs. 59.4%. The QoL between AZD1222®-vaccinated individuals and BBV152®-vaccinated individuals at a month post-vaccination was 0.95±0.13 vs. 0.95±0.126, at 6 months it was 0.98±0.08 vs. 0.97±0.07, and at 12 months it was 0.94±0.12 vs. 0.92±0.20. However, there was no statistically significant difference in the prevalence of PCVS and QoL between AZD1222® and BBV152®-vaccinated individuals.The percentage of participants who had at least one PCVS was 83.9% (146) in the group that got booster doses and 50.2% (117) in the group that did not. The QoL was 0.9±0.15 in the group receiving booster dosages and 0.96±0.11 in the group not receiving them. There was a statistically significant difference in the prevalence of PCVS and QoL between booster dose recipients and no booster dose recipients. ConclusionIn the study, we observed the prevalence of PCVS and was similar to long-term COVID; it declined over time and increased following booster immunization. Contrary to PCVS prevalence, QoL rises with time and falls after booster doses. There is no difference in the prevalence of PCVS and the quality of life among AZD1222® and BBV152®.