The association of online search interest with polio cases and vaccine coverage: an infodemiological and ecological study

Achievement of universal eradication of paralytic poliomyelitis has remained a challenge. Despite the general decline in cases, multiple outbreaks attributed to poor vaccination still occur. Noncompliance from vaccination can be improved through education on various media platforms. In the internet age, online health-seeking behavior plays a significant role in this regard. Hence, our study investigated the association between global online search interest in polio with the number of polio cases and vaccination coverage. This infodemiological and ecological study utilized Google Trends' search volume index (SVI) for "polio" and the World Health Organization data on the number of polio cases (PC) and vaccine coverage rate (VCR) per country between 2006 and 2019. Associations between SVI for "polio" with PC and with VCR were evaluated. From the years 2006 to 2019, the global inquiry for this term was highest (i.e., SVI at 100) last October 2018. There was a direct correlation between the SVI for "polio" and PC while there was an inverse relationship between SVI and VCR per country per year. Both relationships have weak to moderate strength of associations. Based on our models, a one-unit increase in the SVI leads to a 3.8% increase in the number of polio cases. On the other hand, a one-unit increase in the SVI leads to a 0.01% decrease in the VCR. Conclusions: Dynamic changes in global SVIs for polio may reflect fluctuations in the number of polio cases and rates of vaccine coverage. Our study brings into light the largely untapped and potential use of online search behavior for polio to anticipate changes in PC and VCR in real-time.