Evaluation of COVID-19 Vaccines in Primary Prevention Against Infections and Reduction in Severity of Illness Following the Outbreak of Sars-Cov-2 Omicron Variant in Shanghai
Author(s)
Yang D1, Weng H2, Song Y1, Li J3, Lu X3, Yang W2, Chen Z4, Xuan J3, Bai C1, Wang Y5
1Department of Pulmonary and Critical Care Medicine, Zhongshan Hospital Fudan University, Shanghai, China, 2Suvalue Healthcare Scientific Co.,Ltd., Shanghai, China, 3Shanghai Centennial Scientific Co., Ltd, Shanghai, China, 4Department of Clinical Research Management Office, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China, 5Wound Trauma Medical Center, State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Surgery Research, Daping Hospital, Army Medical University, Chongqing, China
Presentation Documents
OBJECTIVES: To evaluate COVID-19 vaccines in primary prevention against infections and lessening the severity of illness following the most recent outbreak of the SARS-CoV-2 Omicron variant in Shanghai.
METHODS: To investigate whether inactivated vaccines were effective in protecting against COVID-19 infections, we estimated the odds ratio (OR) of the vaccination in COVID-19 cases vs. matched community-based healthy controls. To evaluate the potential benefits of vaccination in lowering the risk of symptomatic infection (vs. asymptomatic), we estimated the relative risk (RR) of symptomatic infections among diagnosed patients. We also applied the multivariate stepwise Logistic regression analyses to measure the risk of disease severity (symptomatic vs. asymptomatic and moderate/severe vs. mild) in COVID-19 patient cohort with vaccination status as an independent variable while controlling for potential confounding factors.
RESULTS: Out of the 153,544 COVID-19 patients included in the analysis, 118,124 (76.9%) patients had been vaccinated and 143,225(93.3%) were asymptomatic patients. Of the 10,319 symptomatic patients, 10,031(97.2%), 281(2.7%) and 7(0.1%) experienced mild, moderate, and severe infections, respectively. There is no evidence that the vaccination helped protect from infections (OR=0.82, p=0.613). The vaccination, however, offered a small but significant protection against symptomatic infections (RR=0.92, p < 0.001) and halved the risk of moderate/severe infections (OR=0.48, 95% CI: 0.37 - 0.61). Older age (> 60 years) and malignant tumors were significantly associated with moderate/severe infections. Gender also appeared to be a risk factor for symptomatic infections, with females being associated with a lower risk for moderate/severe illness.
CONCLUSIONS: Inactivated COVID-19 vaccines helped provide a small but significant protection against symptomatic infections and halved risk of moderate/severe illness among symptomatic patients. The vaccination was not effective in blocking COVID-19 Omicron variant community spread.
Conference/Value in Health Info
Value in Health, Volume 26, Issue 6, S2 (June 2023)
Code
EPH100
Disease
Vaccines