The elderly persons, in particular older males, should take the Covid-19 booster dose to protect themselves from breakthrough infections, suggests a recent study published in the journal Clinical Infectious Diseases.¹

In this study, the researchers sought to investigate the antibody response to Covid-19 vaccination among the elderly and the very elderly population. For this, they procured plasma samples from 82 participants aged 75-98 years from the Johns Hopkins Longitudinal Influenza Immunization Study of Aging cohort before and after they took 3 doses of Covid-19 mRNA vaccine. Those with immunocompromised conditions or past history of Covid-19 were not included in the study. Samples were also collected from younger adults, aged 18-74 years, after the second dose of the vaccine. Data from the two groups were compared.

The antibody levels were 1 to 3 times lower among older males compared to their female counterparts. The antibody response was lower among the older and frail male subjects. Compared to the younger population, the antibody responses were 3- to 8-folds lower among the older participants. When antibody titers to the Omicron variant, a similar response was observed with older males having lower antibody levels than older females. At 6 months post vaccination, the antibody response declined. The antibody response however recovered when tested one month after administration of the booster dose and was comparable to those in the younger age group. Although the initial antibody response was stronger in the older females, the levels became equivalent among the male and female older study subjects after the booster dose.

This study has demonstrated the gender differences in antibody response post-vaccination among the elderly subjects. Frailty also had an adverse impact on antibody titers. These findings suggest that low antibody response following primary vaccination with two vaccine doses may put the elderly frail population at risk of breakthrough infections. Hence, they must be encouraged to take the booster dose as and when they are eligible to receive it to protect themselves from the infection.

Reference

1. Janna R Shapiro, et al. Association of frailty, age, and biological sex with severe acute respiratory syndrome coronavirus 2 messenger RNA vaccine-induced immunity in older adults. Clin Infect Dis. 2022 Aug 15;75(Supplement_1):S61-S71. doi: 10.1093/cid/ciac397.