Waning anti-SARS-CoV-2 neutralizing antibody in CoronaVac-vaccinated individuals in Indonesia

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

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1 Citation (Scopus)


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 neutralizing antibody (NAb) anti-SRBD 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 NAb titre was measured using Elecsys Anti-SARS-CoV-2 S immunoassay. A set of standardized and validated questionnaires were used to assess the demographics and other plausible associated factors. Results: Our results showed waning SARS-Cov-2 NAb titres over time post-vaccination. Compared to samples of the first month post-vaccination, the levels of NAb titres were significantly lower than those of five-months (mean 184.6 vs. 101.8 IU/mL, p = 0.009) and six-months post-vaccination (mean 184.6 vs. 95.59 IU/mL, p = 0.001). This suggests that the length of time post-vaccination was negatively correlated with antibody anti-SRBD titre. A protective level of NAbs titres (threshold of 15 IU/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 against SARS-CoV-2, respectively. The titre of NAb anti-SRBD 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 IU/mL, p = 0.044), including in subgroup analysis that included those five to six months post-vaccination only (mean 79.0 vs. 134.5 IU/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.

Original languageEnglish
Article number300
Publication statusPublished - 2022


  • anti-SRBD
  • CoronaVac
  • COVID-19
  • neutralizing antibody
  • Sinovac


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