COVID-19 Evidence Alerts
from McMaster PLUSTM

Current best evidence for clinical care (more info)

Primary Prevention Li X, Yang X, Ning Z Efficacy and safety of COVID-19 inactivated vaccine: A meta-analysis. Front Med (Lausanne). 2022 Nov 7;9:1015184. doi: 10.3389/fmed.2022.1015184. eCollection 2022.
PICO Terms
adult (P) adverse reactions; safety (O) all-cause death (O) allergy (O) aluminum hydroxide (I/C) any infection (O) asymptomatic infection (O) Covaxin vaccine; BBV152; Bharat Biotech; inactivated virus (I/C) fully vaccinated (I/C) healthy (P) hospitalization (O) IBM CAMS/Institute of Medical Biology; inactivated vaccine (I/C) KCONVAC; Vero Cells; inactivated vaccine; Shenzhen Kangtai Biological Products (I/C) placebo (I/C) reactogenicity (O) Sinopharm vaccine; China National Biotec Group Company; Wuhan-WIV04; Beijing-HBO2; BBIBP-CorV; Vero Cells; inactivated virus (I/C) Sinovac vaccine; CoronaVac; inactivated virus (I/C) symptomatic infection (O) vaccine efficacy (O)

BACKGROUND: Inactivated vaccine is one of the primary technology types of Coronavirus Disease 2019 (COVID-19) vaccines, which has wide application in many countries, including mainland China. However, systematic evaluation of the efficacy and safety of COVID-19 inactivated vaccines remains limited. And trust in the vaccine is the key to solving vaccine hesitancy.

METHODS: Various academic databases were searched comprehensively for randomized controlled trials (RCTs) related to COVID-19 inactivated vaccines. The deadline for retrieval was December 2021. Study screening and data extraction were according to inclusive and exclusive criteria. Statistical analyses were performed using RevMan software 5.3 version and STATA software 16.0 version.

RESULTS: Eight studies with 79,334 subjects were included of which 48,123 had received two doses of COVID-19 inactivated vaccines, and 31,211 had received two doses of placebo. The results of the meta-analysis showed that: in terms of effectiveness evaluation, two doses of COVID-19 inactivated vaccines decreased the symptomatic infection [relative risk (RR) = 0.23, 95% confidence interval (CI) (0.18,0.30), P < 0.00001], asymptomatic infection [RR = 0.48, 95%CI (0.32, 0.74), P = 0.0008], total infection [RR = 0.32, 95%CI (0.24, 0.41), P < 0.00001] and hospitalization [RR = 0.06, 95%CI (0.01, 0.27), P = 0.0002] for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) significantly. In terms of safety assessment, two doses of COVID-19 inactivated vaccines also caused more adverse events. After two inoculations, total adverse events and systemic adverse events increased significantly [total adverse events RR = 1.14, 95%CI (1.08, 1.21), P < 0.00001; systemic adverse events RR = 1.22, 95%CI (1.09, 1.35), P = 0.0002]. The most common adverse event was pain at the injection site. Almost all local adverse reactions consisted of these events. The incidence of pain at the injection site was related to adjuvants. Using aluminum hydroxide as an adjuvant increased local pain significantly [RR = 1.97, 95%CI (1.52, 2.55), P < 0.00001]. Two doses COVID-19 inactivated vaccines did not increase serious adverse events [RR = 0.71, 95%CI (0.57, 0.90), P = 0.004].

CONCLUSION: Two doses of inactivated COVID-19 vaccines in people over 18 years of age effectively prevented SARS-CoV-2 infection and its associated hospitalizations. Short-term, mild to moderate adverse reactions had occurred, but serious adverse events were rare. No placebo or vaccine-related deaths had been reported.

SYSTEMATIC REVIEW REGISTRATION:, identifier: 42021291250.

Discipline / Specialty Area Score
Public Health
Internal Medicine
Infectious Disease
Comments from MORE raters

Infectious Disease rater

Meta-analysis quantifying the efficacy and describing the vaccine-associated adverse reactions to inactivated virus SARS CoV-2 vaccines.

Internal Medicine rater

This article is important in providing efficacy and safety information on inactivated COVID-19 vaccine. A lot of data are available on the mRNA vaccine efficacy and safety, but this article provides a meta-analysis of RCTs for the inactivated vaccines that have been widely used in some countries. This is important evidence for my patients who received the inactivated COVID-19 vaccine mainly from China-based manufacturers.