Emerging application of Google Trends searches on "conjunctivitis" for tracing the course of COVID-19 pandemic.

Google Trends searches on conjunctivitis were significantly correlated with COVID-19 daily new cases during the first wave in Italy, France, United Kingdom, and United States, with a lag of 14-18 days. Repeating the analysis for the second wave, however, no significant correlations were found in any of the investigated countries.