Association of Homologous and Heterologous Vaccine Boosters With SARS-CoV-2 Infection in BBIBP-CorV Vaccinated Healthcare Personnel.

Vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have played a crucial role in mitigating the coronavirus disease 2019 (COVID-19) pandemic. However, few studies have addressed the optimal booster vaccine type in recipients of the primary series of BBIBP-CorV (an inactivated virus vaccine developed by Sinopharm). This study aimed to estimate the association between the heterologous or homologous COVID-19 vaccination and SARS-CoV-2 infection. The study enrolled healthcare personnel (HCP) who had completed two doses of BBIBP-CorV between November 2020 and September 2021. The associations between SARS-CoV-2 infection and boosters were measured using multivariable logistic regression, comparing the odds of a positive COVID-19 test result between the no booster group and booster groups (BNT162b2 {Pfizer-BioNTech COVID-19 vaccine} group and BBIBP-CorV group, respectively). A total of 495 HCP comprising 326 (65.9%) in the BNT162b2 group, 121 (24.4%) in the no booster group, and 48 (9.7%) in the BBIBP-CorV group enrolled. One hundred thirty-six cases (27.5%) tested positive for COVID-19. The odds ratios for testing positive after booster dose were 0.401 (95% CI: 0.187-0.860, p = 0.019) and 0.446 (95% CI: 0.170-1.167, p = 0.100) for BNT162b2 and BBIBP-CorV group, respectively. The BNT162b2 booster in HCP after a second dose of BBIBP-CorV, relative to no booster, and the BBIBP-CorV booster, was associated with protection against laboratory-confirmed COVID-19.