We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Estimation of Vaccine Effectiveness of CoronaVac and BNT162b2 Against Severe Outcomes Over Time Among Patients With SARS-CoV-2 Omicron.
- Authors
Wei, Yuchen; Jia, Katherine Min; Zhao, Shi; Hung, Chi Tim; Mok, Chris Ka Pun; Poon, Paul Kwok Ming; Man Leung, Eman Yee; Wang, Maggie Haitian; Yam, Carrie Ho Kwan; Chow, Tsz Yu; Guo, Zihao; Yeoh, Eng Kiong; Chong, Ka Chun
- Abstract
Key Points: Question: Does vaccine effectiveness against hospitalization and mortality due to the SARS-CoV-2 Omicron variant change over time? Findings: In this case-control study with 164 151 participants, the CoronaVac and BNT162b2 vaccines were generally estimated to be effective against severe outcomes due to SARS-CoV-2 Omicron infection, but protection among older individuals was more likely to wane 6 months after the second dose. Meaning: These findings suggest that a booster dose should be recommended to older individuals to restore immunity, and this is especially urgent for a setting like Hong Kong, where third-dose coverage is still insufficient among older residents. This case-control study examines change over time in estimated vaccine effectiveness against hospitalization and mortality caused by the SARS-CoV-2 Omicron variant among adults in Hong Kong. Importance: Few studies have evaluated the waning of vaccine effectiveness against severe outcomes caused by SARS-CoV-2 Omicron infection. Hong Kong is providing inactivated and mRNA vaccines, but the population had limited protection from natural infections before the Omicron variant emerged. Objective: To examine the change in vaccine effectiveness against hospitalization and mortality due to the Omicron variant over time. Design, Setting, and Participants: This case-control study included adults with SARS-CoV-2 Omicron variant infection who died or were hospitalized in Hong Kong from January 1 to June 5, 2022 (ie, case participants), and adults with SARS-CoV-2 Omicron, sampled from the public health registry during the study period (ie, control participants), who were matched to case participants by propensity score. Exposures: Vaccination status of the individuals. Main Outcomes and Measures: Estimated vaccine effectiveness against death, death or hospitalization, and death among hospitalized patients. Vaccine effectiveness was calculated as 1 − adjusted odds ratio obtained by conditional logistic regression adjusted with covariates for each period following vaccination. Results: There were 32 823 case participants (25 546 [77.8%] ≥65 years; 16 930 [47.4%] female) and 131 328 control participants (100 041 [76.2%] ≥65 years; 66 625 [46.6%] female) in the sample analyzed for the death or hospitalization outcome. Vaccine effectiveness against death or hospitalization was maintained for at least 6 months after the second dose of both CoronaVac (74.0%; 95% CI, 71.8%-75.8%) and BNT162b2 (77.4%; 95% CI, 75.5%-79.0%) vaccines. Vaccine effectiveness against death in those aged 18 to 49 years was 86.4% (95% CI, 85.8%-87.0%) and 92.9% (95% CI, 92.6%-93.2%) for those receiving 2 doses of CoronaVac and BNT162b2, respectively, while for patients aged 80 years or older, it dropped to 61.4% (95% CI, 59.8%-63.2%) and 52.7% (95% CI, 50.2%-55.6%) for CoronaVac and BNT162b2, respectively. Nevertheless, overall vaccine effectiveness against death at 4 to 6 months after the third dose was greater than 90% for CoronaVac, BNT162b2, and the mixed vaccine schedule (eg, mixed vaccines: vaccine effectiveness, 92.2%; 95% CI, 89.2%-95.1%). Conclusions and Relevance: While vaccines were generally estimated to be effective against severe outcomes caused by SARS-CoV-2 Omicron infection, this analysis found that protection in older patients was more likely to wane 6 months after the second dose. Hence, a booster dose is recommended for older patients to restore immunity. This is especially critical in a setting like Hong Kong, where third-dose coverage is still insufficient among older residents.
- Subjects
HONG Kong (China); COVID-19; COVID-19 vaccines; MORTALITY; VACCINE effectiveness; TREATMENT effectiveness; HOSPITAL care; RESEARCH funding
- Publication
JAMA Network Open, 2023, Vol 6, Issue 1, pe2254777
- ISSN
2574-3805
- Publication type
Article
- DOI
10.1001/jamanetworkopen.2022.54777