Objective To explore influencing factors of coronavirus disease 2019 (COVID-19) infection among close contacts of COVID-19 cases in Fujian province for providing evidences to the development of effective control measures and intervention strategies.
Methods We recruited 103 locally laboratory-confirmed COVID-19 cases reported from January through March, 2020 in Fujian province; the age (± 5 years)- and region (in the same county/district)-matched controls were 430 persons randomly selected from close contacts completing medical observation in designated quarantine sites and with negative results of throat swab coronavirus nucleic acid detection at 1-, 7-, 14-day of isolation period. The participants′ information was collected online with a self-designed questionnaire. Logistic regression was conducted to analyze influencing factors of COVID-19 infection.
Results There were no significant differences in gender, age, and body mass index between cases and controls (all P > 0.05). Compared to those of the controls, the proportions of the cases reporting following conditions/behaviors were significantly higher: with chronic disease (37.86% vs. 24.65%), co-habitation with confirmed COVID-19 patient (35.92% vs. 15.35%), having daily conversation with confirmed COVID-19 patient (40.78% vs. 23.72%), contacting with symptomatic COVID-19 patient (71.84% vs. 50.93%), contacting with fever COVID-19 patient (48.54% vs. 25.81%), contacting one-time with COVID-19 patient at a distance of one meter or less in close indoor environment for one hour and more (59.22% vs. 30.47%), contacting with COVID-19 patient several times at a distance of one meter or less in close indoor environment cumulatively for 5 hours and more (40.78% vs. 14.65%), contacting with COVID-19 patient several times at a distance of 2 meters or less in close indoor environment cumulatively for 10 hours and more (12.62% vs. 6.74%), contacting with COVID-19 patient at a distance of one meter or less in outdoor environment for 2 hours and more only one time (5.83% vs. 0.47%), and contacting with COVID-19 patient several times at a distance of one meter or less in outdoor environment cumulatively for 10 hours and more (3.88% vs. 0.47%) (all P < 0.05); but there were significantly lower proportions of the cases reporting current smoking (8.74% vs. 26.74%), washing hands frequently (59.22% vs. 74.65%), using soap or liquid soap almost every time when washing hands (32.04% vs. 56.51%), wearing a mask every time when going out (38.83% vs. 70.00%), checking the quality of a mask to be used (13.59% vs. 29.77%), using a new mask all the time when needing mask-wearing (26.21% vs. 36.98%), without direct contact with COVID-19 patient when coexisting in the same close indoor environment with the patient (10.68% vs. 28.14%), taking protective measures when contacting with COVID-19 patient (39.81 vs. 55.81%), conducting hand-washing and other disinfection procedures after contacting with suspected COVID-19 patient (6.80% vs. 28.14%), and ever going to farmers' market two weeks before the disease incidence (67.96% vs. 81.40%) (P < 0.05 for all). Unconditional multivariate logistic regression analysis revealed that ever contacting with symptomatic COVID-19 patient and contacting one-time with COVID-19 patient at a distance of one meter or less in close indoor environment for one hour and more were significant risk factors of COVID-19 infection; the analysis also indicated that wearing a mask every time when going out, checking the quality of a mask to be used, and conducting hand-washing and other disinfection procedures after contacting with suspected COVID-19 patient were significant protective factors against COVID-19 infection.
Conclusion Mask-wearing when going out, checking the quality of a mask to be used, contacting with symptomatic COVID-19 patient, conducting hand-washing and other disinfection procedures after contacting with suspected COVID-19 patient, and contacting one-time with COVID-19 patient at a distance of one meter or less in close indoor environment for one hour and more are significant influencing factors of COVID-19 infection among close contacts of confirmed COVID-19 cases in Fujian province.
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