Review of covid-19 vaccines and their evidence in older adults

Abstract

Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavi-rus 2 (SARS-CoV-2) has resulted in a global pandemic and significant loss of life. Older people are vulnerable to SARS-CoV-2 infections and complications; thus, they are a priority group to re-ceive COVID-19 vaccines. This review discusses considerations for COVID-19 vaccines for older adults. The general concepts of vaccine effectiveness in older adults are described, particularly immune senescence and vaccine development approaches to improve immunogenicity. The types of COVID-19 vaccine platforms are also described before reviewing the available, although limit-ed, evidence from phase 3 COVID-19 vaccine trials relevant to older adults. The BNT162b2 vaccine by Pfizer-BioNTech and mRNA-1273 vaccine from Moderna demonstrated high efficacy and immunogenicity, which were also observed in older people. While the ChAdOx1 nCoV-19 vaccine (AZD1222) by AstraZeneca demonstrated some efficacy in older people, the vaccine dose requires clarification through further studies. Finally, the Ad26.COV2.S vaccine by Janssen Pharmaceuti-cals shows promise as a single-dose vaccine with a potential durability of response.