Online queries as a criterion for evaluating epidemiological status and effectiveness of COVID-19 control measures in Russia: results from Yandex.Wordstat analysis

OBJECTIVES: Assessment of the significance of online queries regarding smell impairment to evaluate the epidemiological status and effectiveness of COVID-19 epidemic control measures using levofloxacin as an example. SETTING: There are 81 regions of Russia and several large cities, such as Moscow, St. Petersburg and Nizhny Novgorod. METHODS: Weekly online queries from Yandex Russian users regarding smell impairment and levofloxacin were analysed in regions and large cities of Russia from 16 March 2020 to 21 February 2021. RESULTS: A strong positive direct correlation (r>0.7) was found between the number of smell-related queries in Yandex new cases of COVID-19 in 59 out of 85 Russian regions and large cities (70%). During the ‘first’ peak of COVID-19 incidence in Russia (April–May 2020), the increase in the number of smell-related queries outpaced the increase in new cases by 1–2 weeks in 23 out of 59 regions of Russia. During the ‘second’ peak of COVID-19 incidence in Russia (October–December 2020), the increase in the number of smell-related queries outpaced the increase in the number of new cases by 1–2 weeks in 36 regions of Russia, including Moscow. It was found that the query/new case ratio increased by more than 100% in 24 regions. The regions where the increase in queries was more than 160% compared with new infection cases during the ‘second’ peak of incidence demonstrated significantly higher search activity related to levofloxacin than the regions where the increase in queries was lower than 160% compared with the increase in new infection cases. CONCLUSION: The sudden interest in certain symptoms of COVID-19, such as smell impairment and the growing frequency of online queries among the population, can be used as an indicator of the spread of coronavirus infection among the population and for evaluation of the effectiveness of the COVID-19 epidemic control measures.