Relationship between COVID-19 and headache: evidence from an infodemiological analysis

Abstract Background: There is emerging evidence that headache may be a frequent common symptom in patients diagnosed with coronavirus disease 2019 (COVID-19), thus paving the way to further epidemiological studies to better evaluate this potential association.Methods: We conducted an electronic search in Google Trends with the keyword “headache” (i.e., “mal di testa”, in Italian), with the geographical area set to “Italy” and the search period comprised between February 2020 and June 2022. The number of new weekly diagnoses of COVID-19 was also captured using the official statistics published by the Italian Ministry of Health. The potential association between Google searches for headache and new COVID-19 diagnoses was verified with Spearman’s correlation.Results: The number of new COVID-19 diagnoses and Google searches for headache in Italy followed a similar trend, nearly overlapping, and yielding a significant correlation during the same week (r=0.56; 95%CI, 0.42-0.67; p<0.001). An even better correlation was found when the number of new COVID-19 diagnoses was correlated with the Google searches for headache in the preceding week (r=0.60; 95%CI, 0.47-0.70; p<0.001).Conclusion: Web interest and, therefore, burden of headache is significantly correlated with the number of newly diagnosed cases of COVID-19 in Italy. This evidence may hence lead the way to using an infodemiological analysis based on the symptom “headache” for timely predicting future trends of COVID-19 outbreaks.