European Journal of Biomedical and Pharmaceutical Sciences

IMMUNOGENICITY, SAFETY, AND EFFICACY OF COVID-19 VACCINES: A SYSTEMATIC REVIEW OF THE LITERATURE

Tarik Chmitah*, Sofia Fellah, Mohamed El Arbi Tahiri Alaoui, Mohamed Amine Sehhar,
Salaheddine Soltani, Jalal Kasouati, Larbi El Bouaiti, Karim Sbai Idrissi

ABSTRACT

Objective: To systematically evaluate the safety, immunogenicity, and protective efficacy of COVID-19 vaccines in the general population. Methods: PubMed and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched to identify phase I/II/III randomized controlled trials of COVID-19 vaccines published up to November 2021. Results: Thirty-eight studies met the inclusion criteria, comprising 35 randomized clinical trials, 2 non-randomized clinical trials, and 1 observational study. The descending order of vaccines according to the ratio of neutralizing-antibody titers in vaccinated versus convalescent sera was: mRNA-1273, NVX-CoV2373, BNT162b2, AZD1222, Ad26.COV2.S, Sputnik V, BBV152, BBIBP-CorV, and CoronaVac. Production of neutralizing antibodies against the SARS-CoV-2 receptor-binding domain in more than 90% of vaccinees was reported within 30 days of the first or second vaccine dose. BNT162b2, mRNA-1273, Sputnik V, and CoronaVac, after two doses, showed the best efficacy (>80%) in preventing symptomatic cases in Phase III trials. mRNA vaccines, AZD1222, and CoronaVac were effective in preventing symptomatic COVID-19 infection and severe disease against the Alpha, Beta, and Gamma variants. Most adverse events were mild to moderate and transient; injection-site pain was the most common local event across vaccine types, while fever, fatigue, and headache were the most common systemic events. Rare serious adverse events were observed with the AZD1222 and Ad26.COV2.S vaccines. Conclusion: Most COVID-19 vaccines appear to be effective and safe. Clinical trial data on long-term protection and protection against multiple variants remain limited. Further research is needed to investigate the long-term efficacy and safety of these vaccines, and the influence of dose, age, and manufacturing process on protective efficacy.

Keywords: COVID-19; SARS-CoV-2; Vaccines; Immunogenicity; Efficacy; Safety; Systematic review.