TABLE 1.

Characteristics of the included studies (Global, 2021).

No.	Citation (First author et al., year)	No. of studies in meta-analysis	Clinical trial phase	Study groups	Purpose	Intervention	Outcome	Evidence level
1	Fan et al. [20]	12	Phase 3	Vaccine group and control group	Safety and efficacy	mRNA, non-replicating viral vector, and inactivated vaccines	Efficacy: two mRNA vaccine doses were associated with lesser risk of SARS-CoV-2 infection than did vaccination with viral vector and inactivated vaccines. Safety: While the vaccines provided greater protection against symptomatic cases as compared to asymptomatic ones, they did decrease the chances of severe SARS-CoV-2 infection	Weak
2	Cheng et al. [12]	8	Phase 3	Vaccine group and placebo group	Safety and efficacy	mRNA, non-replicating viral vector, and inactivated vaccines	Efficacy: the preventive effect of all vaccines on COVID-19 was good, with the mRNA vaccine proving to be the most effective while the inactivated vaccine was least effective. Safety: the vaccine group showed an overall increase in the risk of adverse events after either the first or second injection. Nonetheless, the risk of local and systemic adverse events was lower after the second injection in comparison to the first	Weak
3	Pormohammad et al. [10]	123	Phase 2/3	Adenovirus-based, inactivated, alum, Matrix-M1, AS03, etc.	Safety and efficacy	Adenovirus-based and mRNA-based	Efficacy: the phase 2 and 3 randomized controlled trials showed that mRNA-based vaccines and adenovirus-vectored COVID-19 vaccines had an efficacy of 94.6% and 80.2%, respectively. The adenovirus-vectored vaccine exhibited the highest efficacy against the receptor-binding domain antigen 3 weeks after the first and second doses. Safety: the mRNA-based vaccines had a higher incidence of reported side effects, except for diarrhea and arthralgia. Among vaccines with or without adjuvants, those with aluminum had the least local and systemic side effects, except for injection site redness	Weak
4	Sathian et al. [29]	12	Phase 1/2/3	Vaccine	Safety	Vaccine	The prevalence of adverse events was 35% after pooling the data	Suggestive
5	Greenhawt et al. [14]	41	NA	Vaccine in the United States and Canada	Safety (polyethylene glycol allergy)	Vaccine	Canada’s polyethylene glycol allergy is 42.63% per million person-years, compared to only 0.01% in the United States	Weak
6	Zheng et al. [11]	51	NA	BNT162b2, mRNA, ChAdOx1 nCoV-19, etc.	Effectiveness	BNT162b2, mRNA, ChAdOx1 nCoV-19, etc.	Vaccine effectiveness in fully vaccinated populations shows efficacy against severe acute respiratory syndrome coronavirus 2 infection, COVID-19-related hospitalization, admission to the intensive care unit, and death, at rates of 89.1%, 97.2%, 97.4%, and 99.0%, respectively	Weak
7	Cai et al. [15]	22	1/2/3	Ad26, COV2.S, ChAdOx1, RNA-based, and viral vector	Safety (thromboembolic events and myocarditis/pericarditis events)	Inactivated, protein subunit, RNA-based, and viral vector (non-replicating and replicating) vaccines	High efficacy and tolerable adverse drug reactions make vaccines a powerful tool in controlling the COVID-19 pandemic	Weak
8	Ling et al. [21]	9	NA	Vaccine group and control group	Safety (adverse events)	Inactivated virus, RNA, and adenovirus vector vaccines	Safety: adverse reactions are more common with the three vaccines compared to a placebo, and the adenovirus vector vaccine has a higher incidence of adverse reactions	Highly Suggestive
9	Naranbhai et al. [30]	15	NA	Vaccine, and breakthrough cases	Effectiveness	mRNA1273, BNT162b2, and Ad26.COV2.S vaccines	BNT162b2 was found to be less effective than mRNA1273 at preventing infection and hospitalization, while Ad26COV2.S was less effective against infection, hospitalization, and death	Weak
10	McDonald et al. [22]	55	Phase 1/2/3	Vaccine group and control group	Safety	mRNA, BNT162b1, and ChAdOx vaccines	The vaccinated group had an increased risk of adverse events compared to the control group, with the Polack31/BNT162b2 mRNA vaccine associated with an increased risk and the Baden27/mRNA-1273 vaccine with an increased risk	Highly Suggestive
11	Liu et al. [23]	32 for effectiveness and 26 for safety	NA	Vaccinated people with SARS-CoV-2 infection and unvaccinated people with SARA-CoV-2 infection	Safety and effectiveness	BNT162b2, AZD1222, and mRNA-1273 vaccines	COVID-19 vaccines are generally safe and effective at reducing the severity and spread of COVID-19	Suggestive
12	Chen et al. [26]	14	NA	Inactivated, vectored, and mRNA vaccines	Safety	Inactivated, vectored, and mRNA vaccines	COVID-19 vaccines are well-tolerated and safe for widespread use, with inactivated vaccine candidates causing the fewest adverse events post-immunization	Weak
13	Wu et al. [24]	53 records in support of safety determinations of 19 COVID-19 candidate vaccines on 6 platforms, 11 observational studies reporting the safety profiles of 6 COVID-19 vaccines, and 20 publications reporting the safety profiles of 4 COVID-19 vaccines from monitoring data	NA	Different vaccines	Safety	mRNA, non-replicating vector, protein subunit, virus-like particle, DNA, etc.	Current data suggests that eligible COVID-19 vaccines have acceptable short-term safety profiles	Weak
14	Kow et al. [31]	19	NA	Different vaccines	Effectiveness	BNT162b2 mRNA vaccines	The first dose of the vaccine provided a 53% effectiveness rate against RT-PCR-confirmed COVID-19 at least 14 days post-vaccination, and the second dose provided a 95% effectiveness rate at least 7 days after administration. Nervous and muscular adverse events were common but not life-threatening	Weak
15	Alhumaid et al. [25]	5	NA	Different vaccines	Safety (anaphylactic reactions)	Pfizer-BioNTech and Moderna vaccines	The overall pooled prevalence estimates of anaphylaxis for both vaccines was 5.0, while the overall pooled prevalence estimate of nonanaphylactic reactions for both vaccines was 53.9 p= <0.0001)	Weak
16	Chen et al. [34]	15	Phase 1/2	Vaccine group and control group	Safety	Inactivated, replication-incompetent vector, recombinant protein, and mRNA vaccines	Following vaccination, Nervous and muscular adverse events were common, of which headache and myalgia were the most prevalent, although life-threatening unsolicited events were rare	Weak
17	Sharif et al. [27]	7	Phase 1/2/3	Vaccine group and placebo group	Efficacy, immunogenicity and safety	BNT162b2, ChAdOx1 nCoV-19 (AZD1222), rAd26 and rAd5 vector-based (Gam-COVID-Vac), ChAdOx1 nCoV-19 (AZD1222), and mRNA-1273 vaccines	The adenovirus vector vaccine was 73% effective in participants aged 18 and older, while the messenger RNA vaccine had a higher efficacy rate of 85%	Weak
18	Chandan et al. [32]	18	Phase 1/2/3	Fully, partially, and unvaccinated	Effectiveness	mRNA vaccines, BNT162b2 vaccine from Pfizer–BioNTech, and the mRNA‐1273 vaccine from Moderna	The risk of COVID‐19 infection in both partially and fully vaccinated healthcare workers remains exceedingly low when compared to unvaccinated individuals	Weak
19	Uaprasert et al. [28]	8	NA	Vaccine group and placebo group	Safety (thromboembolic and hemorrhagic risks)	BNT162b2 and mRNA-1273 vaccines	There is no evidence to suggest that vaccines against SARS-CoV-2 increase the risk of thromboembolism, hemorrhage, or thromboembolism/hemorrhage-related death	Weak