Estimating natural boosting from antibody titers for measles, rubella, varicella, and mumps among young adults in Japan through 2021.

BACKGROUND

In Japan, measles elimination was declared by WHO in 2013. Outbreaks of rubella were also controlled to elimination. Routine immunization of infants for varicella was begun in October 2014. By contrast, mumps has had outbreaks every 4-5 years.

OBJECT: This study was conducted to elucidate associations between outbreaks in children and antibody titers in adults for measles, rubella, varicella, and mumps.

METHODS

Participants were university students during 2012-2020. When entering university, they were tested using enzyme immunoassay (EIA) for IgG antibodies for the four diseases. Subsequently, we regressed antibody titer data on pediatric outbreaks with lags of several days to 60 days. The estimation procedures were robust regression for the log of titer, logistic regression for the protection level, and the Wilcoxon rank sum test. Particularly, we excluded effects of outliers who were presumed to have been infected recently prior.

RESULTS

Estimation results demonstrated that an outbreak occurring among children affects immunity in young adults with a several day lag, and particularly within a 60 day lag for rubella, varicella, and mumps. However, no such association with measles was found for measles.

DISCUSSION AND

CONCLUSION

We identified the possibility of natural boosting for rubella, varicella, and mumps, but no natural boosting was found for measles.