Use of Google Trends to investigate loss-of-smell-related searches during the COVID-19 outbreak

Int Forum Allergy Rhinol. 2020 Jul;10(7):839-847. doi: 10.1002/alr.22580. Epub 2020 Jun 15.

Abstract

Background: Initial reports describing coronavirus 2019 (COVID-19) were dominated by the presence of cough, breathlessness, and fever; anecdotal reports suggested anosmia may also be a manifestation. We used Google Trends (GT) to investigate whether there was a surge in individuals searching for information related to smell loss during the COVID-19 epidemic in Italy, Spain, the United Kingdom, the United States, Germany, France, Iran, and The Netherlands.

Methods: GT was used to explore internet activity related to loss of smell in the 8 aforementioned countries. Spearman rank analysis was performed to correlate loss-of-smell-relative search volumes (RSVs), with the increases of daily confirmed cases of COVID-19 and deaths attributed to disease. As a control event, we also performed analysis of smell-related searches during the last UK influenza epidemic of 2009.

Results: In all 8 countries, we observed strong correlations between daily RSVs related to loss of smell, increases of daily COVID-19+ cases and deaths ranging from 0.633 to 0.952. All correlations were statistically significant (p < 0.05).

Conclusion: There is a strong correlation between the frequency of searches for smell-related information and the onset of COVID-19 infection in Italy, Spain, UK, USA, Germany, France, Iran, and The Netherlands. We hypothesize this may relate to a previously underrecognized symptom.

Keywords: COVID-19; Google Trends; coronavirus; loss of smell; symptom variation.

MeSH terms

  • Betacoronavirus
  • COVID-19
  • Coronavirus Infections / epidemiology*
  • Europe / epidemiology
  • Humans
  • Iran / epidemiology
  • Olfaction Disorders / epidemiology*
  • Pandemics
  • Pneumonia, Viral / epidemiology*
  • Population Surveillance
  • SARS-CoV-2
  • Search Engine / statistics & numerical data
  • Search Engine / trends*
  • United States / epidemiology