Anti-RBD antibody quantitation after vaccination against Covid-19 among the elderly in 2021-2022

Abstract

ABSTRACT Background: The study aims to describe the concentration of binding antibodies after COVID-19 vaccination in the elderly in Hanoi and Hung Yen in 2021-2022 and evaluate some related factors. Methods: A prospective cohort study of 205 people aged >= 60 vaccinated with AstraZeneca was conducted in COVID-19 vaccination facilities at Hanoi Medical University Hospital, ALH Nursing Home, Xuan Quan in Van Giang district, Hung Yen province from 9/2021 to 5/2022. The sCOVG test was used to evaluate the concentration of anti-RBD IgG binding antibodies at 7-time points. Results: Antibod concentrations peaked 14 days after the second dose (14.8 IU/ml), and gradually decreased until 3 months after the second dose. However, after the third dose, antibody concentrations increased again (60.24 IU/ml). Women had higher antibody concentrations than men when comparing the median antibody concentration 14 days after the first injection (7.08 vs 3.95 IU/ml) and 14 days after the second injection (32.27 vs. 16.60 IU/ml). People without a history of allergies had higher antibody concentrations than those with a history of allergies when comparing the median at 56 days after the second dose (7 vs. 5 IU/ml). Conclusion: Therefore, we recommend that people pay attention to vaccinating the third dose of the COVID-19 vaccine for elderly people who have not been vaccinated with this vaccine, especially men and elderly with allergies, to minimize the prevalence and mortality. Keywords: Anti-RBD, COVID-19 vaccine, AstraZeneca, Pfizer, elderly