Efficacy of Sinopharm Vaccine Among Healthcare Workers of Pakistan

Background: The advent of a vaccine for COVID-19 has been a breakthrough to prevent infection from the virus. The objective of this study was to compare the frequency and severity of COVID-19 infection among vaccinated and non-vaccinated healthcare workers (HCWs). Methods: This was a prospective cohort study conducted on HCWs at Liaquat National Hospital, Karachi. The participants n=2500 were recruited before (November 2020 to January 2021) and after vaccination (February 2021 to May 2021). A detailed history including vaccination status, from the patients, was taken by treating physicians. All recruited patients were followed up for three months for upper respiratory tract symptoms. Chi-square test/Fisher exact was applied for associations. Poisson regression was applied to compute the incidence rate. A p-value ≤0.05 was defined as statistically significant. Results: The 2500 participants were included in each group of this cohort study. The median age of unvaccinated and vaccinated healthcare workers was 33 (27 – 42.5) years and 35(29 – 45) years respectively. During three months, 166 (6.64%) workers acquired COVID-19 infection yielding an incidence of 7.6 per 10,000 person-days. All the cases were mild and were managed at their home during their quarantine period. Within 3 weeks after the first dose, 2(0.08%) workers had COVID-19 infection with an incidence rate of 0.4 per 10,000 person-days. After administration of the second dose, 4(0.16%) found COVID-19 positive within 21 days with an incidence of 0.8 per 10,000 person-days. Conclusion: Vaccine provides significant (p