AUTHOR=Li Xiaoming , Yang Xia , Ning Zong 

TITLE=Efficacy and safety of COVID-19 inactivated vaccine: A meta-analysis

JOURNAL=Frontiers in Medicine

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2022.1015184

DOI=10.3389/fmed.2022.1015184

ISSN=2296-858X

ABSTRACT=Background: Inactivated vaccine is one of the primary technology types of Coronavirus Disease 2019 (COVID-19) vaccines, which are wide application in many countries, including mainland China. However, systematic evaluation of the efficacy and safety on COVID-19 inactivated vaccines remains limited. And trust in the vaccine is the key to solving vaccine hesitancy.
Method: Various academic databases were searched comprehensively for randomized controlled trials(RCTs) related to COVID-19 inactivated vaccine. The deadline for retrieval was December 2021. Study screening and data extraction were according to inclusive and exclusive criteria. At last, we performed statistical analyses with RevMan software 5.3 version and STATA software 16.0 version.
Result: Eight studies with 79334 subjects were included, 48123 received 2-doses COVID-19 inactivated vaccines, and 31211 received 2-doses placeboes. The results of meta-analysis showed that: ①In terms of effectiveness evaluation, 2-doses 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 SARS-CoV-2 significantly. ②In terms of safety assessment, 2-doses COVID-19 inactivated vaccines also caused more adverse events. After twice 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]. ③The 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]. ④2-doses COVID-19 inactivated vaccines did not increased serious adverse events [RR=0.71, 95%CI (0.57,0.90), P=0.004].

Conclusion: 2-doses inactivated COVID-19 vaccines in people over 18 years old 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: https://www.crd.york.ac.uk/prospero/identifier:42021291250.