中島 裕史

The effect of antibodies elicited by bivalent mRNA vaccines (original and omicron BA.1) on preventing coronavirus disease 2019 (COVID-19) onset in the presence of the XBB variant remains unknown. A prospective cohort study conducted at Chiba University Hospital examined healthcare workers who received their sixth vaccination with the Pfizer-BioNTech COVID-19 bivalent mRNA vaccine (original and omicron BA.1). Researchers quantitatively measured serum anti-spike (S) antibody levels. Participants not infected during the 60-day observation period after vaccination had significantly higher S antibody titers than those who were newly infected (27756 U/mL, 95% CI [24988-30831 U/mL] vs. 15321 U/mL, 95% CI [10824-21688 U/mL], p<0.05). The risk of infection decreased by 84% when the S antibody titer exceeded 15500 U/ml. Neutralizing antibody titers against the XBB.1.16 and XBB.1.42 variants were higher in age- and sex-matched noninfected individuals than in newly infected individuals during the post-vaccination observation period. S antibody titers were highly correlated with neutralizing antibody titers. In conclusion, after the sixth COVID-19 vaccination with the bivalent mRNA vaccine (original and omicron BA.1), high S antibody titers correlated with disease prevention, even in the presence of XBB variants.

Introduction: So far, no definitive conclusions have been reached regarding the preventive effect of moisturizers on atopic dermatitis (AD). The variability in results may be due to differences in skin care methods, including bathing and washing, among studies and study design. In hot and humid Japan, bathing and gauze washing have been routinely practiced from the neonatal period, but this may impair the skin barrier function. To address this gap, we determined whether a combination of minimally invasive cleaning methods and moisturizing may prevent AD in infants in Japan. Methods: Mothers of children born between January and September 2019 were instructed in traditional skin care methods (control group; 132 subjects), and mothers of children born between January and September 2020 were instructed in a new skin care method combining less invasive washing and moisturizing (intervention group; 140 subjects). Mothers and babies with and without a history of allergy were recruited, and the incidence of AD at 1 year of age was investigated by questionnaire. Results: Skin care-related behaviors such as face washing, hand washing, and use of moisturizers were more frequent in the intervention group than in the control group. At 6 and 12 months of age, there was no difference in the incidence of AD between the two groups. However, for children born between January and March, the prevalence of AD at 12 months was significantly lower in the intervention group than in the control group (2.9% vs. 21.2%, p = 0.0253). Conclusions: This study suggests that for children born during dry and cold seasons, strengthening the skin barrier function early in life through routine skin care with less invasive washing and moisturizing may prevent AD in Japan. Appropriate skin care practices for newborns and infants may vary in regions and environments.