Safety and Immunogenicity of SARS-Cov-2 Vaccine MVC-COV1901– Do Elderly Need a Higher Dose?

Older adults are subject to higher COVID-19 infection and mortality rates. Even though vaccination programs prioritize the elderly, they are under-represented in clinical trials. Safety and immunogenicity of MVC-COV1901, a protein subunit vaccine has been demonstrated in phase 2 clinical trial for the general population, and negative correlations have been observed between immune responses and age. To further assess safety and immunogenicity of MVC-COV1901 vaccine in participants of 65 years and older, a double-blind, randomized, multi-center study compared high-dose (25 mcg) to mid-dose (15 mcg) of MVC-COV1901 administered 2 times 28 days apart. The results have been stratified by the comorbidity status. Both high and mid-dose regimens elicited mostly mild adverse events and robust immune responses when measured as neutralizing and binding antibodies titers. High doses elicited better immune responses in the group without comorbidities. Given the general population-associated safety and immunogenicity of MVC-COV1901, we recommended high dose for the elderly.