Objective  To explore risk factors of 2019 novel coronavirus (2019-nCoV) infection for close contacts of 2019 novel coronavirus disease (COVID-19) cases in Guangzhou city.

  Methods  We enrolled 2 593 close contacts of confirmed, suspected, and asymptomatic COVID-19 cases diagnosed from January 24 to March 2, 2020 in Guangzhou city of Guangdong province. The contacts′ information on demographics, exposure history, and quarantine outcomes were collected and analyzed with descriptive statistics and logistic regression.

  Results  Among all the contacts, 127 were diagnosed as confirmed or asymptomatic COVID-19 cases within the 14-day medical observation, accounting for 36.71% (127/346) of all the COVID-19 cases diagnosed during the period. Of all the confirmed infectees, 113 (88.98%) were the infectors′ family members or relatives; 104 (81.89%) were exposed to the infectors in family settings; 115 (90.55%) had frequent contacts with the infectors; and 107 (84.25%), 88 (69.29%), and 77 (60.63%) reported ever dining, living, and using the same bedroom together with the infector, respectively. Logistic regression analysis revealed following significant risk factors of the infection for the close contacts: being an infector′s family member or relative (odds ratio OR = 4.331, 95% confidence interval 95% CI: 1.009 – 17.063), dining together with an infector (OR = 2.030, 95% CI: 1.037 – 3.975), at elder age (OR = 1.205, 95% CI: 1.095 – 1.326), and frequent contact (OR = 5.516, 95% CI: 3.180 – 9.569).

  Conclusion  The important measures to cut off the spread of the disease in the family are to promoting personal hygienic habit, conducting disinfection of commodities, keeping safe social distance, and having early medical observation are important measure to prevent familial transmission of the coronavirus disease.