When governments mandate chickenpox vaccinations, a sharp drop in the number of Google searches for the common childhood disease suggests seasonal outbreaks are significantly reduced, according to new research from Ann Arbor-based University of Michigan.
The research was led by Kevin Bakker, a doctoral student in the U-M Department of Ecology and Evolutionary Biology. Mr. Bakker and his research team examined thousands of Google searches for the term "chickenpox" across 36 countries during an 11-year period starting in 2004.
The analysis revealed a strong correlation between Google searches for "chickenpox" and the number of reported cases in three countries that require the reporting of chickenpox cases but do not require the vaccine — Mexico, Thailand and Estonia. Additionally, the correlation held, albeit weaker, in two countries that report chickenpox and require the vaccine — the United States and Australia.
The most striking correlations were recorded in countries that implemented a government-mandated vaccination program for the disease and then saw a reduction in the number of searches for "chickenpox." For instance, searches for the term decreased in Germany, as the country's vaccination requirements increased over the course of several years, beginning in 2004.
"These results suggest that information seeking can be used for rapid forecasting, when the reporting of clinical cases is unavailable or too slow," the authors wrote. They also suggested nationwide vaccinations for chickenpox may reduce total disease incidence.
According to Mr. Baker, this is the first study of its kind to use digital epidemiology to demonstrate the effectiveness of a vaccine.
To read Mr. Bakker's full report, click here.
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