- Bakker KM, et al. Proc Natl Acad Sci U S A. May 31, 2016, http://bit.ly/29gPNh6.
Using Google search data, researchers were able to predict chickenpox outbreaks and show vaccines are effective in preventing them. This method of using online data, known as digital epidemiology, can provide information about disease trends even if they are not reported to national health officials.
The team in this study sought to look at the reliability of this approach as well as patterns in chickenpox outbreaks around the world. They used Google Trends to analyze searches for chickenpox from 36 countries on five continents over 11 years and noted seasonal patterns. Spikes in searches tended to come in the spring consistent with previous studies on chickenpox outbreaks.
Researchers compared search trends to clinical data from five countries. In Mexico, Thailand and Estonia where vaccination is not required, searches were significantly correlated with reported cases of the disease. In the U.S. and Australia where vaccination is required, the links were weaker.
“The findings … indicate that immunization programs diminish seasonal information-seeking behavior and likely represent decreased seasonality of outbreaks,” the authors wrote.
This also could be seen in Germany where seasonality of searches dropped after the country began requiring vaccination in 2004. It plunged even more after 2009 when the country required a booster dose.
Researchers also created eight models to forecast the timing and size of outbreaks and found those incorporating Google Trends fared better than those that did not.
“Thus, digital epidemiology is an easily accessible tool that can be used to complement traditional disease surveillance, and may be the only readily available data source for studying seasonal transmission of nonnotifiable diseases in certain instances,” according to the study.
