Effectiveness, Safety, and Immunogenicity of a Second COVID‐19 Vaccine Booster in the Elderly: A Systematic Review and Meta‐Analysis Protocol

Abstract

Older adults remain highly vulnerable to severe COVID‐19 outcomes due to immunosenescence and comorbidities. Although booster vaccination strategies have reduced hospitalizations and mortality, evidence regarding the effectiveness, safety, and immunogenicity of a second COVID‐19 vaccine booster dose in older adults remains fragmented. This systematic review and meta‐analysis protocol aims to critically evaluate the available evidence from randomized and nonrandomized clinical trials (NRCTs) regarding the effectiveness, safety, and immunogenicity of the second COVID‐19 vaccine booster in older adults worldwide.