Real-world COVID-19 vaccine effectiveness against the Omicron BA.2 variant in a SARS-CoV-2 infection-naive population

• Published in: Nature medicine Vol. 29; no. 2; pp. 348 - 357
• Main Authors: Lau, Jonathan J., Cheng, Samuel M. S., Leung, Kathy, Lee, Cheuk Kwong, Hachim, Asmaa, Tsang, Leo C. H., Yam, Kenny W. H., Chaothai, Sara, Kwan, Kelvin K. H., Chai, Zacary Y. H., Lo, Tiffany H. K., Mori, Masashi, Wu, Chao, Valkenburg, Sophie A., Amarasinghe, Gaya K., Lau, Eric H. Y., Hui, David S. C., Leung, Gabriel M., Peiris, Malik, Wu, Joseph T.
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.02.2023; Nature Publishing Group
• Subjects: 631/250/590; 631/326/596/4130; 692/699/255/2514; 692/700/478/174; Biomedical and Life Sciences; Biomedicine; BNT162 Vaccine; Cancer Research; Coronaviruses; COVID-19; COVID-19 Vaccines; Effectiveness; Health risks; Humans; Immunization; Infections; Infectious Diseases; Local population; Metabolic Diseases; Molecular Medicine; Neurosciences; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Signs and symptoms; Vaccine Efficacy; Vaccines; Viral diseases; Hong Kong China; China
• ISSN: 1078-8956; 1546-170X; 1546-170X
• DOI: 10.1038/s41591-023-02219-5

The SARS-CoV-2 Omicron variant has demonstrated enhanced transmissibility and escape of vaccine-derived immunity. Although first-generation vaccines remain effective against severe disease and death, robust evidence on vaccine effectiveness (VE) against all Omicron infections, irrespective of symptoms, remains sparse. We used a community-wide serosurvey with 5,310 subjects to estimate how vaccination histories modulated risk of infection in infection-naive Hong Kong during a large wave of Omicron BA.2 epidemic in January–July 2022. We estimated that Omicron infected 45% (41–48%) of the local population. Three and four doses of BNT162b2 or CoronaVac were effective against Omicron infection 7 days after vaccination (VE of 48% (95% credible interval 34–64%) and 69% (46–98%) for three and four doses of BNT162b2, respectively; VE of 30% (1–66%) and 56% (6–97%) for three and four doses of CoronaVac, respectively). At 100 days after immunization, VE waned to 26% (7–41%) and 35% (10–71%) for three and four doses of BNT162b2, and to 6% (0–29%) and 11% (0–54%) for three and four doses of CoronaVac. The rapid waning of VE against infection conferred by first-generation vaccines and an increasingly complex viral evolutionary landscape highlight the necessity for rapidly deploying updated vaccines followed by vigilant monitoring of VE. An analysis of sera samples collected between January and July of 2022 in Hong Kong shows that the effectiveness of both the BNT162b2 and CoronaVac COVID-19 vaccines against SARS-CoV-2 Omicron BA.2 variant infection waned rapidly after the third and fourth doses.