Manaf AlQahtani, Sujoy Bhattacharyya, Abdulla Alawadi, Hamad Al Mahmeed, Jaleela Al Sayed, Jessica Justman, Wafaa M. El-Sadr, Jack Hidary, Siddhartha Mukherjee
The emergence of new SARS-CoV-2 variants across the world has raised concerns about the effectiveness of available COVID-19 vaccines that were designed against the original Wuhan (wild type) variant. Critical questions have arisen regarding: (a) the effectiveness of various vaccines in preventing infection, symptomatic disease, hospitalization, intensive care unit (ICU) admission and death and (b) the magnitude and clinical consequences of post-vaccination infections in the context of emerging variants, especially the Delta variant of SARS-Cov2. While “real world” experiences with various vaccines have been reported, few have examined comparative effectiveness of various vaccines in one population, as new SARS-CoV-2 variants have emerged. Here we present an analysis of COVID-19 related outcomes from Bahrain, a country with a total population of 1.501 million, where four vaccines were deployed (total vaccinated =1,003,960), including Astra-Zeneca (AZ/Covishield), Pfizer/BioNtech, Sinopharm and Sputnik V. By analyzing individual histories of vaccinated versus unvaccinated cases, we provide a granular description of the effectiveness of the four vaccines, disease burden in unvaccinated versus vaccinated individuals over time, and the risk of four outcomes (infections, hospitalizations, ICU admissions and deaths) due to breakthrough infections among vaccinated individuals. We conclude that the four vaccines were effective in reducing all four outcomes in vaccinated compared to unvaccinated individuals, prior to, and during the period when the Delta variant became dominant in the country (May 2021 to the present). However, after censoring early vaccine recipients of Sinopharm vaccine, compared to Pfizer/BionTech recipients, individuals vaccinated with Sinopharm had a higher risk of post-vaccination infections, hospitalizations, ICU admissions and deaths, especially in those > 50 years old. Our overall findings support the value of vaccination in preventing COVID-19 related events even with the advent of the Delta variant. These data support the urgent need to expand vaccination access around the world, and may serve to guide the choice of vaccines in the context of the Delta variant.