A Randomized Clinical Trial Using CoronaVac or BNT162b2 Vaccine as a Third Dose in Adults Vaccinated with Two Doses of CoronaVac

• Published in: American journal of respiratory and critical care medicine Vol. 205; no. 7; pp. 844 - 847
• Main Authors: Mok, Chris Ka Pun, Chen, Chunke, Yiu, Karen, Chan, Tat-On, Lai, Kiu Cheung, Ling, Kwun Cheung, Sun, Yuanxin, Hui, David S., Cheng, Samuel M. S., Peiris, Malik
• Format: Journal Article
• Language: English
• Published: United States American Thoracic Society 01.04.2022
• Subjects: Adult; BNT162 Vaccine; Clinical trials; COVID-19 Vaccines; Humans; Immunization; Older people; Vaccines
• ISSN: 1073-449X; 1535-4970; 1535-4970
• DOI: 10.1164/rccm.202111-2655LE

CoronaVac is a World Health Organization approved inactivated virus vaccination that has been given to over 750 million people in over 40 countries. CoronaVac showed efficacies against symptomatic disease of 50.65 percent, 65.30 percent, and 83.50 percent in phase three randomized clinical trials (RCTs) in Brazil, Indonesia, and Turkey, respectively. The impact of antibody fading on virus variations has not been studied because these efficacy studies analyzed outcomes within a few months of vaccination. Breakthrough infections have been documented in CoronaVac-vaccinated persons, some of which have resulted in severe disease and death. CoronaVac's immunogenicity is substantially lower than the BNT162b2 mRNA vaccine, according to a recent observational study, and we projected that declining immunity would result in a loss of protection.