Harapan Harapan, Hibban Ar Royan, Islam Ing Tyas, Auda Nadira, Irham Faraby Abdi, Samsul Anwar, Milda Husnah, Ichsan Ichsan, Agung Pranata, Mudatsir Mudatsir, Maimun Syukri, Samsul Rizal, Razali, Hamdani, Rudi Kurniawan, Irwansyah Irwansyah, Sarwo Edhy Sofyan
Background: The decrease of immunity acquired from COVID-19 vaccines is a potential cause of breakthrough infection. Understanding the dynamics of immune responses of vaccine-induced antibodies post-vaccination is important. This study aimed to measure the level of anti-SARS-CoV-2 receptor-binding domain (RBD) total antibody in individuals at different time points upon the receipt of the second dose of CoronaVac vaccine, as well as evaluate the plausible associated factors. Methods: A cross-sectional study was conducted among CoronaVac-vaccinated residents in Banda Aceh, Indonesia. The level of anti-SARS-CoV-2 RBD total antibody was measured using Elecsys immunoassay. A set of standardized and validated questionnaires were used to assess the demographics and other associated factors. Results: Our results showed waning anti-SARS-CoV-2 RBD total antibody titres over time post-vaccination. Compared to samples of the first month post-vaccination, the antibody titres were significantly lower than those of five-months (mean 184.6 vs. 101.8 U/mL, p = 0.009) and six-months post-vaccination (mean 184.6 vs. 95.59 U/mL, p = 0.001). This suggests that the length of time post-vaccination was negatively correlated with titre of antibody. A protective level of antibody titres (threshold of 15 U/mL) was observed from all the samples vaccinated within one to three months; however, only 73.7% and 78.9% of the sera from five- and six-months possessed the protective titres, respectively. The titre of antibody was found significantly higher in sera of individuals having a regular healthy meal intake compared to those who did not (mean 136.7 vs. 110.4 U/mL, p = 0.044), including in subgroup analysis that included those five to six months post-vaccination only (mean 79.0 vs. 134.5 U/mL, p = 0.009). Conclusions: This study provides insights on the efficacy of CoronaVac vaccine in protecting individuals against SARS-CoV-2 infection over time, which may contribute to future vaccination policy management to improve and prolong protective strategy. Copyright: © 2023 Harapan H et al.
Medical Research Unit, School of Medicine, Universitas Syiah Kuala, Banda Aceh, 23111, Indonesia; Department of Microbiology, School of Medicine, Universitas Syiah Kuala, Banda Aceh, 23111, Indonesia; Tropical Disease Centre, School of Medicine, Universitas Syiah Kuala, Banda Aceh, 23111, Indonesia; Department of Statistics, Faculty of Mathematics and Natural Sciences, Universitas Syiah Kuala, Banda Aceh, 23111, Indonesia; Tsunami and Disaster Mitigation Research Center (TDMRC), Universitas Syiah Kuala, Banda Aceh, 23111, Indonesia; Department of Parasitology, School of Medicine, Universitas Syiah Kuala, Banda Aceh, 23111, Indonesia; Department of Internal Medicine, School of Medicine, Universitas Syiah Kuala, Banda Aceh, 23111, Indonesia; Department of Mechanical and Industrial Engineering, Faculty of Engineering, Universitas Syiah Kuala, Banda Aceh, 23111, Indonesia
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