Fig. 2

Standardized Partial Regression Coefficient of Factors. Abbreviations: Meeting relatives or friends: Meeting relatives or friends coming from Hubei in the past month; Present symptoms: Present symptoms of SARS-CoV-2 infection; Suspicion: Suspicion of SARS-CoV-2 infection; Knowledge: Knowledge about personal protective measures. Chronic diseases included hypertension, hyperlipidemia, diabetes, asthma, chronic obstructive pulmonary disease (COPD), chronic bronchitis, heart disease, gout, thyroid nodules, thyroid cancer, and lung cancer. Regular physical activity was defined as regular exercise within the recent six months. Current smoker was defined as an adult who has smoked 100 cigarettes in his or her lifetime and who currently smokes cigarettes; former smoker was defined as an adult who has smoked at least 100 cigarettes in his or her lifetime but who had quit smoking at the time of interview; while non-smoker was defined as an adult who has never smoked, or who has smoked less than 100 cigarettes in his or her lifetime. Current drinker was defined as at least 12 drinks in the past year; former drinker was defined as at least 12 drinks in any one year in lifetime but no drinks in past year; while non-drinker was defined as fewer than 12 drinks in lifetime. Contact history was defined as close contact with a confirmed or suspected case of COVID-19 without taking precautions. Gatherings and meetings were defined as been to a company meeting or a family dinner in the last two weeks. Present symptoms of SARS-CoV-2 infection included fever, cough, runny nose, sore throat, shortness of breath, fatigue, nasal congestion, headache, vomiting and diarrhea