Fig 1.
Numbers of daily subjects’ recruitment on baseline (closed dots; Y1-axis: numbers of subjects) were shown together with the number of daily newly confirmed COVID-19 cases (open dots; Y2-axis: numbers of COVID-19 cases) in Sleman District [26]. Public health measures and COVID-19 vaccination policy starting events (marked with vertical lines on the graph) are also included in the figure. The first stage of Community Activities Restrictions Enforcement (CARE) was implemented in January 2021 and the second stage of CARE was started in July 2021. Timeline of baseline, monitoring 1 (4–5 weeks post inclusion) and monitoring 2 (8–9 weeks post inclusion) is depicted at the base of the figure, ilustrating the duration of recruitment from April 2021 to Decemeber 2021, with the final monitoring completed in February 2022 (grey area).
Fig 2.
Inclusion of study participants and group analysis.
Note: Of the 24 subjects not analyzed, 17 and 15 interviews and plasma data points were missing at monitoring 1 and 2, respectively.
Table 1.
Characteristics of the study population based on patients’ anti-RBD-SARS-CoV-2 IgG status at baseline.
Table 2.
Correlations among demographics, clinical status, possible transmission of infection, and vaccination status with anti-RBD-SARS-CoV-2 IgG seropositivity.
Table 3.
Overall characteristics by group of study participants by unvaccinated and vaccinated group status on baseline.
Fig 3.
Comparison of anti-RBD IgG antibody levels against SARS-CoV-2 at baseline, monitoring 1 (Mon-1; 4–5 weeks post-baseline) and monitoring 2 (Mon-2; 8–9 weeks post-baseline) in the population in Sleman District, Indonesia.
The numbers of subjects with IgG anti-RBD SARS-CoV-2 seropositivity (+/-) and postinclusion (PI) vaccination status (“yes/no”) at each data sampling point are depicted underneath each graph. Anti-RBD-SARS-CoV-2 IgG seropositivity = ≥ 50 AU/mL; the P-values for each monitoring session were calculated using the Wilcoxon matched-pair signed rank test. P≤ 0.05 was considered to indicate statistical significance.
Fig 4.
Comparison of groups without and with postinclusion (PI) vaccination during monitoring 1 (4–5 weeks PI) and monitoring 2 (8–9 weeks) in the four groups.
Within Groups 2 and 4, PI vaccination included those who received second dose of the vaccine, while in Groups 1 and 3, PI vaccination consisted of 1–2 doses of the vaccine. The median of P-value was analyzed the Wilcoxon matched-pair signed rank test, and P≤0.05 was considered to indicate statistical significance.