Fluctuations in antibody titers against enterovirus D68 in pediatric sera collected in a community before, during, and after a possible outbreak.

We previously reported a hospital-based epidemiological study on enterovirus (EV)-D68 infection among children during the autumn of 2015, which indirectly inferred an outbreak in Sendai, Japan. In this study, stocked sera of children (aged 0-6 years; without symptoms of infectious diseases) in the Sendai community collected during 4 periods (1 year before, 6 months before, immediately after, and 1 year after the possible outbreak period) were analyzed using the neutralization antibody titer assay to determine community children's immunity levels against EV-D68 infection. The immunity levels were confirmed to have increased during the possible outbreak period and to have gradually waned over 1 year without another outbreak. These results provide background information supporting the results of our previous hospital-based surveillance study.