Temporary Fertility Decline after Large Rubella Outbreak, Japan

Area of Science:

• Public Health
• Epidemiology
• Demography

Background:

• Japan has faced recurrent rubella epidemics, with significant outbreaks in 2004 and 2012-2014, and a subsequent resurgence from 2018-2020.
• Suboptimal immunization coverage has contributed to the persistence of rubella outbreaks in Japan.
• Rubella infection during pregnancy can lead to congenital rubella syndrome, impacting birth rates.

Purpose of the Study:

• To analyze the impact of the 2012-2014 rubella epidemic on natality rates at the prefecture level in Japan.
• To investigate the correlation between rubella epidemic activity and fertility trends.
• To assess public interest in rubella through search engine query data.

Main Methods:

• Time series analyses were employed to evaluate the relationship between rubella epidemic data and natality.
• Prefecture-level fertility rates were compared against rubella incidence.
• Google search trends for "rubella" were analyzed to gauge public awareness and concern.

Main Results:

• A statistically significant decline in fertility rates was observed, correlating with rubella epidemic activity.
• Increased Google searches for "rubella" coincided with epidemic periods.
• Fertility declines in 2014 were temporally linked (9-13 months post-peak incidence) to the 2013 rubella outbreak in high-incidence prefectures.

Conclusions:

• Rubella epidemics can lead to measurable decreases in birth rates.
• Enhanced rubella vaccination campaigns are crucial for public health.
• Interventions should aim to protect pregnant women and mitigate demographic impacts from rubella outbreaks.