The COVID-19 Vaccine Booster Shots: Do We Really Need a Third Dose? – A Review

  • Farah Khalid Department of Pharmacy Practice, Dow College of Pharmacy, Dow University of Health Sciences, Karachi, Pakistan
  • Hina Zahid Department of Pharmacognosy, Dow College of Pharmacy, Dow University of Health Sciences, Karachi, Pakistan.
Keywords: SARS-CoV-2, Vaccine booster, COVID-19 variants


Background: The global reappearance of COVID-19, propelled primarily by the delta and omicron variant of SARS-CoV-2. Due to reoccurrence, the administration of COVID -19 booster shots has been considered by many countries to address impending declining immunity with the passage of time and decreased efficacy against the COVID-19 variants. The introduction of new combination of vaccines against SARS-CoV2 variants showed enhanced immunity against these variants.

Objectives: The objective of this review is to highlight the requirement of COVID-19 vaccine booster shots against evolving variants. We aimed to use the data repositories like, FDA, CDC, WHO and research articles to assess the usefulness of third dose of vaccine for preventing rise in COVID-19 cases.

Methodology: We have included English language articles in this review. The literature was investigated in PubMed and Google Scholar by use of systematic keywords. The articles are included from 2021 – 2022 and no exclusion criteria were set. 

Results: The modification in the SARS-CoV-2 virulence appeared in the form of its different variants like Beta, Gamma, Delta and Omicron necessitates the administration of booster shots. Apart from the emergence of variants, the unpredictable immunity level globally as demonstrated from the ambiguous data also contributes for the need of third COVID-19 vaccine dose. To achieve immunity against evolving variants the FDA has approved the mix and match administration of different vaccines including Moderna, AstraZeneca, Pfizer-BioNTech and Janssen/Johnson & Johnson. The geriatric population and immunocompromised patients ranked as the first recipient of third booster shot because of already weakened immune system. Emphasis was also given for the accelerated and complete vaccination of population belongs to lower income countries, as the majority are yet to be vaccinated with the first dose.

Conclusion: In conclusion, research data suggests that a third dose of COVID -19 vaccine is effective in protecting the individual compared with receiving only one or two doses.

Review Article