ABSTRACT
Background: It was found that more than half of the population in Korea had a prior COVID-19 infection. In 2022, most nonpharmaceutical interventions, except mask-wearing indoors, had been lifted. Discussions about easing the indoor mask mandate are ongoing. Methods We developed an age-structured compartmental model that distinguishes vaccination history, prior infection, and medical staff from the rest of the population. Contact patterns among hosts were separated based on age and location. We simulated scenarios with the lifting of the mask mandate all at once or sequentially according to the locations. Furthermore, we investigated the impact of a new variant assuming that it has higher transmissibility and risk of breakthrough infection. Findings We found that the peak size of administered severe patients might not exceed 1,100 when the mask mandate is lifted everywhere, and 800 if the mask mandate only remains in the hospital. If the mask mandate is lifted in a sequence (except hospital), then the peak size of administered severe patients did not exceed 650. Moreover, if the new variant have both of higher transmissibility and immune reduction therefore the effective reproductive number of the new variant is approximately 3 times higher than the current variant, additional interventions may be needed to keep the administered severe patients from exceeding 2,000, which is the critical level we set. Interpretation Our findings showed that the lifting of the mask mandate, except in hospitals, would be applicable more manageable if it is implemented sequentially. Considering a new variant, we found that depending on the population immunity and transmissibility of the variant, wearing masks and other interventions may be necessary for controlling the disease.
Subject(s)
COVID-19 , Breakthrough PainABSTRACT
Messenger RNA (mRNA) vaccination has been implemented to mitigate the coronavirus disease 2019 pandemic. However, data on antibody kinetics and factors influencing mRNA vaccines’ immunogenicity are limited. We conducted a prospective study on healthy young adults who received two doses of the mRNA-1273 vaccine at 28-day intervals. After each dose, adverse events were prospectively evaluated and blood samples were collected. The correlation between humoral immune response and reactogenicity after vaccination was determined. In 177 participants (19–55 years), the geometric mean titers of the anti-S IgG antibody were 178.07 and 4409.61 U/mL, whereas those of 50% neutralizing titers were 479.95 and 2851.67 U/mL 4 weeks after the first and second doses, respectively. The anti-S IgG antibody titers were not associated with local reactogenicity, but they were significantly higher in participants who experienced systemic adverse events (fever, headache, and muscle pain). Antipyretic use was an independent predictive factor of strong anti-SARS-CoV-2 antibody response after receiving both doses. Systemic reactogenicity after the first dose influenced antibody response after the second dose. mRNA-1273 induced a robust antibody response in healthy young adults. Post-vaccination immunogenicity might be related to systemic reactogenicity. Antipyretic use did not decrease the anti-SARS-CoV-2 antibody response after mRNA-1273 vaccination. Funding: This work was supported by the Korea National Institute of Health, Korea Disease Control and Prevention Agency [2021ER260300].