Abstract:

Objective: To measure incidence, disease severity and outcome of COVID-19 Vaccine Breakthrough Infections among Health Care Workers (HCWs) and Support Staff completely vaccinated with Sinopharm Vaccine. Study Design: Prospective cohort study. Place and Duration of Study: All Military Health facilities of Pakistan reporting COVID-19 cases post vaccination, from Jul to Sep 2021. Methodology: Established Surveillance Mechanism for getting post vaccination COVID-19 cases from various health care settings of Pakistan Army enabled the collection of data on prescribed data forms. Among HCWs and support staff vaccinated with both doses or single dose regimen of COVID-19 vaccine; those who developed COVID-19 infection ≥14 days post 2nd dose were included in the study. Total 327 participants from 1st Jul till 30th September 2021 fulfilled the criteria and data pertaining to them was further analyzed. Results: Mean age of the participants was 32.38 ± 9.18 years. Males were 73.4% and 26.6% were females. Median duration from 2nd dose to development of vaccine breakthrough infection was 133 days (Inter Quartile Range: 55 days). Asymptomatic /mild infections were reported among 97.9% and only 1.5% had moderate disease. However, 0.6% reported severe/critical disease and required ventilator support. Most 79.2% breakthrough infections ocuured almost more than 3 months completion of vaccination and only 20.8% developed it before three months. Among all, 99.4% recovered completely while 0.4% couldn’t survive the complications associated with COVID-19. There was no significant statistical association of job category with disease severity (p>0.05) Conclusion: Vaccines still remain a powerful tool in war against COVID-19. No vaccine has yet to be found 100% effective against all variants of concern (VoCs) however less severe disease and mortality was observed after vaccination. Waning immunity after three months needs administration of booster dose of vaccine to HCWs and support staff working in a highly exposed environment of health facilities.

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