It remains unknown whether the Indonesian healthcare workers (HCWs) who had received two doses of CoronaVac vaccine and one dose of mRNA-1273 booster could be protected during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron wave. In total, 125 infection-naïve and 10 previously infected HCWs were recruited. The mRNA-1273 booster substantially increased titer of anti-SARS-CoV-2 spike protein receptor-binding domain antibodies. However, the monitoring revealed that 34 out of 125 infection-naïve (27.2%) and 3 out of 10 previously infected HCWs (30.0%) were infected during the Omicron wave. All infected HCWs were either asymptomatic or having mild coronavirus disease 2019 (COVID-19) and subsequently fully recovered, supporting the heterologous prime-boost strategy against COVID-19.

Purpose: This study was performed to investigate humoral immune response and adverse events upon the heterologous prime-boost with a single dose of the mRNA-1273 vaccine among fully CoronaVac-vaccinated, infection-naïve healthcare workers in Indonesia. Materials and Methods: One hundred twenty-five eligible healthcare workers were recruited from one hospital for this prospective cohort study. Blood collection was conducted twice, i.e., on 7 days before and 28 days after the booster vaccination. The titer of anti-SARS-CoV-2 receptor-binding domain (RBD) antibodies was quantified accordingly. The post-vaccination adverse event was recorded for both CoronaVac and mRNA-1273 vaccinations. Any breakthrough infection was monitored during the follow-up period. Wilcoxon matched-pairs signed rank test was used to test differences between groups. Results: A significant increase was observed in the titer of anti-SARS-CoV-2 RBD antibodies upon receiving the mRNA-1273 booster (geometric mean titers of 65.57 and 47,445 U/mL in pre- and post-booster, respectively), supporting the argument to use heterologous prime-boost vaccination to improve the protection against COVID-19 in a high-risk population. The mRNA-1273 vaccine, however, caused a higher frequency of adverse events than the CoronaVac vaccine. Nonetheless, the adverse events were considered minor medical events and temporary as all subjects were not hospitalized and fully recovered. Of note, no breakthrough infection was observed during the follow-up to 12 weeks post-booster. Conclusion The heterologous prime-boost vaccination of healthcare workers with a single dose of the mRNA-1273 vaccine generated a significant elevation in humoral immune response towards RBD of SARS-CoV-2 and was associated with a higher frequency, but minor and transient, adverse events.

Purpose: We reported a survey-based study assessing the parental intention to vaccinate children of 5 to 7 years old against coronavirus disease 2019 (COVID-19). The aim of this study is to assess factors influencing the parental intention to vaccinate their children against COVID-19. Materials and Methods: This study adopted a cross-sectional design, held at the public health center of Senen district, Jakarta, Indonesia from November 1–30, 2022. The off-line questionnaires were distributed via the school administrator to all eligible parents. Factors associated with intention to vaccinate were analyzed with the regression logistic models. Results: Of the 435 parents in this study, 215 had already vaccinated their children against COVID-19 (49.4%), and the overall intention of the participants to vaccinate was 69.7%. Factors associated with intention to vaccinate the children against COVID-19 were parental employment status, parental COVID-19 vaccine status and concern of contracting COVID-19. Parents who are employed, had completed vaccines with COVID-19 booster vaccine, and had concern of their children contracting COVID-19 were more likely to vaccinate their children (odds ratio [OR], 2.10; 95% confidence interval [CI], 1.22–3.69; p=0.011; OR, 2.15; 95% CI, 1.21–3.83; p=0.013; OR, 2.40; 95% CI, 1.34–4.30; p=0.004, respectively). Concern on the vaccine’s side effects was negatively associated with the willingness to vaccinate. Conclusion This study showed that childhood COVID-19 vaccine only covered half of the population, with parental intentions for childhood COVID-19 vaccination being high, reaching almost two-thirds of the study participants. Factors influencing parental intentions were employment status, parental COVID-19 vaccine status, concerns about COVID-19 and concerns about vaccine side effects.