Immunisation reduces seasonal outbreak of chickenpox reveals Google searches

Washington: Human information-seeking behavior aka Google searches reveal that countries which implement government-mandated vaccinations for chickenpox show a sizable reduction in the reported cases over the years.

That's one of the findings from a new University of Michigan-led study that analyzed thousands of Google searches for "chickenpox." The researchers downloaded and analyzed freely available Google Trends data from 36 countries on five continents, covering an 11-year period starting in 2004.

The technique is sometimes called digital epidemiology and has previously been used to identify outbreaks of diseases like influenza, rotavirus and norovirus. But the chickenpox study is the first to use digital epidemiology to show the effectiveness of a vaccine, said Kevin Bakker, a doctoral student in the U-M Department of Ecology and Evolutionary Biology.

"It is really exciting to see human information-seeking behavior Google searches being reduced by vaccination implementation," Bakker said. "It's a very clear signal, and it shows that the vaccine is having a strong effect."

The study is one of the most comprehensive digital epidemiology efforts to date, Bakker said. Examining data from several dozen countries enabled the researchers to identify the seasonality of chickenpox outbreaks, which occurred in the springtime worldwide, he said.

The main idea behind digital epidemiology studies is that the number of Google searches spikes in response to an infectious-disease outbreak as worried parents and others seek information about symptoms, treatment, vaccines and related topics.

The most interesting results, according to Bakker, were analyses showing a reduction in searches for "chickenpox" following the implementation of a government-mandated vaccination program for the disease.

"These results demonstrate that if you institute nationwide vaccination for chickenpox there is a very clear reduction in searches, which is a way to infer a strong reduction in total disease incidence," Bakker said.

Chickenpox is a highly contagious disease caused by the varicella zoster virus. It causes a blister-like rash, itching, tiredness and fever. The rash appears first on the stomach, back and face and then spreads over the entire body, causing between 250 and 500 itchy blisters, according to the Centers for Disease Control and Prevention. In adults, the same virus can cause shingles.

This research has been published in Proceedings of the National Academy of Sciences.