RESUMEN
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.
RESUMEN
BACKGROUND: One of the methods to record immunogenicity after vaccination is to measure antibody titer. This study aimed to get the value of antibody titer post Sinovac vaccination and to analyze factors that associate with it. The trend of titer changes within 3 months period and the incidence of COVID-19 were also observed. METHODS: A prospective cohort study was conducted in March until May 2021 involving 250 health care workers of Siloam Hospitals Lippo-Cikarang who have completed two doses of Sinovac vaccination. We collected 3 titer data from each participant to observe the trend of changes. The incidence of COVID-19 among post-vaccinated subjects was also calculated. RESULTS: From total of 250 participants, 88 (35.2%) were males and 162 (64.8%) were females. Fourteen days after vaccination, 248 subjects (99.2%) had seroconversion. The median antibody titer amounted to 63.58 U/ml (0.4->250 U/ml). The titer was higher in age group 26-39 years (85.1 U/ml, p=0.003) and in women (78.7 U/ml, p=0.007). Within 3 months period, 162 from 200 participants (81%) who completed 3 titer tests, had antibody titer reduction (p=0.231). In observation, 94 from 245 (38.3%) participants tested positive COVID-19, with only 5 out of 94 (5.3%) participants being hospitalized. CONCLUSION: The highest median titer was achieved 14 days after Sinovac vaccination (63.58 U/ml). Younger age group and women are associated with higher value. The reduction trend in titer within 3 months is insignificant. Among post-vaccinated infection subjects, the hospitalization rate is low, which shows that Sinovac vaccination still has a protective effect.
