Author/Authors :
Dadras, Omid Iranian Research Center for HIV/AIDS - Iranian Institute for Reduction of High Risk Behaviors - Tehran University of Medical Sciences, Tehran, Iran , Seyed Alinaghi, Ahmad Iranian Research Center for HIV/AIDS - Iranian Institute for Reduction of High Risk Behaviors - Tehran University of Medical Sciences, Tehran, Iran , Karimi, Amirali School of Medicine - Tehran University of Medical Sciences, Tehran, Iran , Shojaei, Alireza Iranian Research Center for HIV/AIDS - Iranian Institute for Reduction of High Risk Behaviors - Tehran University of Medical Sciences, Tehran, Iran , Amiri, Ava Iranian Research Center for HIV/AIDS - Iranian Institute for Reduction of High Risk Behaviors - Tehran University of Medical Sciences, Tehran, Iran , Mahdiabadi, Sara School of Medicine - Tehran University of Medical Sciences, Tehran, Iran , Fakhfouri, Amirata School of Medicine - Islamic Azad University Tehran branch, Tehran, Iran , Razi, Armin School of Medicine - Tehran University of Medical Sciences, Tehran, Iran , Mojdeganlou, Hengameh Department of Pathology - Urmia University of Medical Sciences, Urmia, Iran , Mojdeganlou, Paniz School of Medicine - Shahid Beheshti University of Medical Sciences, Tehran, Iran , Barzegary, Alireza Department of Pathology - Urmia University of Medical Sciences, Urmia, Iran , Pashaei, Zahra Iranian Research Center for HIV/AIDS - Iranian Institute for Reduction of High Risk Behaviors - Tehran University of Medical Sciences, Tehran, Iran , Afsahi, AmirMasoud Department of Radiology - School of Medicine - University of California, California, USA , Shobeiri, Parnian School of Medicine - Tehran University of Medical Sciences, Tehran, Iran , Mehraeen, Esmaeil Department of Health Information Technology - Khalkhal University of Medical Sciences, Khalkhal, Iran
Abstract :
Introduction: Controversies existed regarding the duration of COVID-19 vaccines’ protection and whether receiving
the usual vaccine doses would be sufficient for long-term immunity. Therefore, we aimed to systematically
review the studies regarding the COVID-19 vaccines’ protection threemonths after getting fully vaccinated
and assess the need for vaccine booster doses. Methods: The relevant literature was searched using a combination
of keywords on the online databases of PubMed, Scopus, Web of Science, and Cochrane on September
17th, 2021. The records were downloaded and the duplicates were removed. Then, the records were evaluated
in a two-step process, consisting of title/abstract and full-text screening processes, and the eligible records were
selected for the qualitative synthesis. We only included original studies that evaluated the efficacy and immunity
of COVID-19 vaccines three months after full vaccination.This review adhered to the Preferred Reporting Items
for Systematic Reviews and Meta-analyses (PRISMA) statement to ensure the reliability of results. Results: Out
of the 797 retrieved records, 12 studies were included, 10 on mRNA-based vaccines and two on inactivated vaccines.
The majority of included studies observed acceptable antibody titers in most of the participants even after
6 months; however,it appeared that the titers could also decrease in a considerable portion of people. Due to the
reduction in antibody titers and vaccine protection, several studies suggested administering the booster dose,
especially for older patients and those with underlying conditions, such as patients with immunodeficiencies.
Conclusion: Studies indicated that vaccine immunity decreases over time, making people more susceptible to
contracting the disease. Besides, new variants are emerging, and the omicron variant is continuing to spread
and escape fromthe immune system, indicating the importance of a booster dose.
