revealing covid-19 breakthrough infection rates among vaccinated individuals at a tertiary care centre in south india

Background and objectives: the covid-19 pandemic was mitigated by the rapid development and deployment of vaccines. while vaccines reduce infection severity, breakthrough infections (btis) still occur. the cdc defines bti as a positive sars-cov-2 test ≥14 days post-vaccination. this study investigates the occurrence of covid-19 btis at a tertiary care hospital in puducherry, south india.materials and methods: this retrospective study analysed hospital tested qrt-pcr data of individuals from the icmr portal (march 2021–march 2022). demographic and vaccination details were extracted.results: among 8001 tested individuals, 1452 were vaccinated. the bti rate decreased from 16.6% to 1.2% after the first dose and from 58% to 40% after the second one. odds ratio indicated a 74% reduction in infection risk for vaccinated individuals compared to unvaccinated. males had higher infection rates than females, regardless of vaccination status.conclusion: our study demonstrates a higher bti rate after one vaccine dose compared to two doses. the bti rate also increased four months post-vaccination, even with two doses, potentially due to waning immunity and the emergence of new variants. therefore, continued adherence to preventive measures in conjunction with vaccination is crucial for minimizing covid-19 transmission.