Meta-Analysis Supports COVID-19 Vaccines for Adults of All Ages

COVID-19 vaccines enhance protection against SARS-CoV-2 infection in people of all ages, according to results from a systematic review and meta-analysis published in the Journal of the Brazilian Society of Tropical Medicine.

“It is recommended that the younger age group, from 18 to 60 years, take the vaccine because of the high response of their immune system,” researchers wrote. “The older age group, over 60 years, may show a slow response rate and low level of immunity; therefore, the second dose would boost immunity and increase the chance of protection.”

The study included 16 randomized controlled trials investigating the immunogenicity of current COVID-19 vaccines in a total 26,698 participants.

Pooled analysis of spike protein neutralizing antibody geometric mean titer significantly favored the vaccine group at 1 and 2 months after vaccination overall regardless of vaccine dose, according to the study. By age group, the difference was significant in adults aged 18 to 55 years but not in older adults. 

“The younger age group responded dramatically to the vaccination and showed a remarkable increase after receiving the second (higher) dose. Immunogenicity in older age groups requires further attention,” the authors wrote. “These unfavorable results can be attributed to immunosenescence, which hinders the innate and adaptive immune response with an increase in age.”

The seroconversion rate of spike protein neutralizing antibodies also favored the vaccine groups at 1 and 2 months after vaccination, researchers reported. 

“Current vaccines can be protective tools for controlling the COVID-19 pandemic and preventing further fatalities. As no vaccine was proven to be more immunogenic, and hence more protective, people should be encouraged to receive the available vaccine in their country,” researchers concluded. “The older age group is worth monitoring for the response of their immune system.”

Reference:
Vasconcelos ZS, Salem HA, Veiga SP, et al. Immunogenicity characterization of COVID-19 vaccines: a systematic review and meta-analysis. Rev Soc Bras Med Trop. Published online January 23, 2023. doi:10.1590/0037-8682-0661-2022