Effectiveness of Covid-19 Vaccines against the SARS-COV-2-Delta (B.1.617.2) in China-A Real World Study

Abstracts Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) delta (B.1.617.2) variant is highly transmissible and has contributed to a surge in cases globally. This study aimed to explore the potential of vaccines against SARS-CoV-2 delta (B.1.617.2) variant in China. Methods In this real-world study, all data were extracted from Xi’an Chest Hospital. Confirmed cases infected with Delta VOC with exact date of positive viral testing were included for analysis. Patients meeting the study criteria were divided into unvaccinated and partially vaccinated (one dose), full vaccinated (two doses), and booster vaccination of COVID-19. Results A total of 455 cases were enrolled in this study. Proportion of severe and critical cases in full vaccinated cases (1.82%) and cases with booster vaccination (1.35%) of COVID-19 were much lower than that of unvaccinated and partially vaccinated cases (8.16%). In addition, cases with booster vaccination (12.78 days) and full vaccinated cases (12.59 days) showed shorter duration of viral shedding than that in unvaccinated and partially vaccinated cases (13.87 days). Conclusion This is the first real world study indicating that Covid-19 vaccines showed much powerful effectiveness against the SARS-COV-2-Delta (B.1.617.2) in China, including lowing the proportion of severe illness and shorting the virus shedding time.