The efficacy and effectiveness of the COVID-19 vaccines in reducing infection, severity, hospitalization, and mortality: a systematic review

Hum Vaccin Immunother. 2022 Dec 31;18(1):2027160. doi: 10.1080/21645515.2022.2027160. Epub 2022 Feb 3.


With the relatively rapid development of the COVID-19 pandemic, vaccine development has become crucial for limiting disease transmission. The accelerated growth in the approved COVID-19 vaccines has sparked concerns about their efficacies which have been assessed by many studies. This systematic review compares the efficacy and effectiveness of seven COVID-19 vaccines. A comprehensive systematic literature search was performed using several databases to identify studies reporting the effectiveness or the efficacy of the vaccines. Only 42 studies met our inclusion criteria, which revealed that the COVID-19 vaccines have successfully reduced the rates of infections, severity, hospitalization, and mortality among the different populations. The full-dose regimen of the Pfizer/BioNTech vaccine is the most effective against infections with the B.1.1.7 and B.1.351 variants. Despite of the high effectiveness of some of the COVID-19 vaccines, more efforts are required to test their effectiveness against the other newly emerging variants.

Keywords: COVID-19; effectiveness; efficacy; vaccine.

Publication types

  • Systematic Review

MeSH terms

  • COVID-19 Vaccines*
  • COVID-19* / prevention & control
  • Hospitalization
  • Humans
  • Pandemics
  • SARS-CoV-2


  • COVID-19 Vaccines

Supplementary concepts

  • SARS-CoV-2 variants

Grants and funding

The author(s) reported there is no funding associated with the work featured in this article.