BACKGROUND: Previous studies have found a strong correlation between internet 
search and public health surveillance data. Less is known about how search data 
respond to public health interventions, such as vaccination, and the consistency 
of responses in different countries. In this study, we aimed to study the 
correlation between internet searches for "rotavirus" and rotavirus disease 
activity in the United States, United Kingdom, and Mexico before and after 
introduction of rotavirus vaccine.
METHODS: We compared time series of internet searches for "rotavirus" from 
Google Trends with rotavirus laboratory reports from the United States and 
United Kingdom and with hospitalizations for acute gastroenteritis in the United 
States and Mexico. Using time and location parameters, Google quantifies an 
internet query share (IQS) to measure the relative search volume for specific 
terms. We analyzed the correlation between IQS and laboratory and 
hospitalization data before and after national vaccine introductions.
RESULTS: There was a strong positive correlation between the rotavirus IQS and 
laboratory reports in the United States (R2 = 0.79) and United Kingdom (R2 = 
0.60) and between the rotavirus IQS and acute gastroenteritis hospitalizations 
in the United States (R2 = 0.87) and Mexico (R2 = 0.69) (P < .0001 for all 
correlations). The correlations were stronger in the prevaccine period than in 
the postvaccine period. After vaccine introduction, the mean rotavirus IQS 
decreased by 40% (95% confidence interval [CI], 25%-55%) in the United States 
and by 70% (95% CI, 55%-86%) in Mexico. In the United Kingdom, there was a loss 
of seasonal variation after vaccine introduction.
CONCLUSIONS: Rotavirus internet search data trends mirrored national rotavirus 
laboratory trends in the United States and United Kingdom and 
gastroenteritis-hospitalization data in the United States and Mexico; lower 
correlations were found after rotavirus vaccine introduction.