Evaluation of risk factors associated with SARS-CoV-2 transmission.

Objective: Coronavirus disease 2019 (COVID-19) has caused high morbidity and mortality worldwide. Since there is not enough evidence of risk factors of SARS-CoV-2 transmission, this study aimed to evaluate them.
Methods: This survey-based study was conducted across 66 countries from May to November 2020 among suspected and confirmed individuals with COVID-19. The stepwise AIC method was utilized to determine the optimal multivariable logistic regression to explore predictive factors of SARS-CoV-2 transmission.
Results: Among 2372 respondents who participated in the study, there were 1172 valid responses. The profession of non-healthcare-worker (OR: 1.77, 95%CI: 1.04-3.00, p  = .032), history of SARS-CoV or MERS-CoV infection (OR: 4.78, 95%CI: 2.34-9.63, p  < .001), higher frequency of contact with colleagues (OR: 1.17, 95%CI: 1.01-1.37, p  = .041), and habit of hugging when greeting (OR: 1.25, 95%CI: 1.00-1.56, p  = .049) were associated with an increased risk of contracting COVID-19. Current smokers had a lower likelihood of having COVID-19 compared to former smokers (OR: 5.41, 95%CI: 1.93-17.49, p  = .002) or non-smokers (OR: 3.69, 95%CI: 1.48-11.11, p  = .01).
Conclusions: Our study suggests several risk factors for SARS-CoV-2 transmission including the profession of non-healthcare workers, history of other coronavirus infections, frequent close contact with colleagues, the habit of hugging when greeting, and smoking status.