Practice of COVID-19 preventive measures and risk of acute respiratory infections: a longitudinal study in students from 95 countries

OBJECTIVES: We aimed to investigate whether the implementation of personal protective measures against COVID-19 reduced the transmission of influenza-like illnesses. METHODS: We followed 758 international students from 95 countries located in 5 continents from October 2020 to March 2021. Their frequency of wearing masks, physical distancing, washing hands, and avoiding crowded places, as well as their reported cases of influenza-like illnesses, were examined. We used Kaplan-Meier analysis to compare the occurrence of symptoms of influenza-like illnesses among participants who adhered with those who did not adhere to the personal protective measures. RESULTS: From October 2020 to March 2021, 139 (18%) students reported symptoms of influenza-like illnesses. The survival analysis showed that students who frequently wore face masks, exercised physical distancing, and disinfected their hands had a reduced risk of influenza-like illnesses. We found a two-fold increased risk of influenza-like illnesses among participants who did not implement all the personal protective measures compared with those who adhered to the measures (hazard ratio=2.16, 95% CI=1.53-3.05, P<0.001). CONCLUSIONS: Our findings suggest that personal protective measures with high feasibility and acceptability could be implemented during influenza epidemics to reduce transmission.