The effect of age on the COVID- 19 vaccines efficacy

Background: Aging leads to a decrease in the function of the immune system. Older people are more vulnerable to infections and have a poor response to vaccines. Age-related changes in the immune system, such as the thymic involution and changes in bone marrow structure, the decrease in the number of naive T and B cells, and the functional defects of the immune cells lead to poor vaccine effectiveness with age. Since age is a risk factor for the severity and mortality of COVID-19 infection, it is necessary to pay attention to the effectiveness of the vaccine in this group..(1-11).Methods: We searched various electronic databases including PubMed, Scopus and Web of Science for related articles until March 2023 using the following keywords according to Medical Subject Heading (Mesh): (Severe Acute Respiratory Syndrome- Coronaviruses-2 OR SARS-C0V-2 OR COVID-19) AND (age OR elderly OR old people) AND (vaccine response OR vaccine immunogenicity) AND antibody response. Abstract and full text of papers were reviewed. There were no restrictions on the publication date of the articles. The inclusion criteria included articles that examined the effectiveness of the COVID-19 vaccines and also evaluated the relationship between age and the effectiveness of the vaccine. Exclusion criteria for this studywere guidebooks, reviews and case-report article. Finally, 30 eligible studies which included in the study. Results: Of the 30 articles included, all articles evaluated vaccine efficacy by measuring post-vaccination antibody titer and examined the relationship of antibody titer or seroconversion rate with age. The results show that age has a negative effect on the antibody response induced by the vaccine and the effectiveness of the vaccine is weaker in the elderly. Conclusion: Due to the decreasing effectiveness of vaccines in the elderly, there is aneed to develop enhanced vaccines (high dose, use of special adjuvants, special platforms and use of senolytic drugs) for the elderly.