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

Previously, we 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 the present study, we collected sera from children (aged 0-6 years; without symptoms of infectious diseases) in the Sendai community during four sample collection periods (1 year before, 6 months before, immediately after, and 1 year after the possible outbreak period). Immunity levels against EV-D68 infection in the children were analyzed by assaying the neutralization antibody titers of the sera. Further, it was confirmed that the immunity levels considerably increased during the possible outbreak period and gradually waned over 1 year in the absence of another outbreak. These results provide background information that supports the results of our previous hospital-based surveillance.