A 1:1 ratio case-control study on coronavirus disease 2019

Objective:To compare the characteristics of COVID-19 patients and healthy people,including living habits and living environment in Danzhou,Hainan province,to provide evidence for policy making for disease control.Methods:Case-control study was used,and the 1:1 control group in Danzhou based on the matching conditions including same age and sex,age±2 years.The main contents of the questionnaire included social democracy characteristics,living habits,living environment,and exposure history.Results:There were 14 COVID-19 patients in Danzhou.In the comparison of the daily habits,it was found that the number of people in the case group who had the habit of wearing masks after catching a cold was lower than that in the control group.And the number of people in the case group who had the habit of spitting was higher than that in the control group.Besides,the results of the survey on eating habits showed that there was less than half of the subjects used serving chopsticks and spoons when having dinner with family members or others,both in the case group and the control group.In the comparison of preferred food types,6 people(42.9%)in the case group preferred cold vegetables,while only 2 people(14.3%)in the control group preferred cold vegetables.In comparison with the travel history and contact history of COVID-19,12 people(85.7%)in the case group had travel history in Wuhan or other regions,but only two in the control group had a history of living in Wuhan or other places.1:1 paired analysis showed that 5 pairs of had habits of spitting in the case group but had no habits of spitting in control group,and 1 pair had habits of spitting in control group but had no habits of spitting in the case group,the OR value was 5.0.Besides,there were 2 pairs of had the habit of wearing a mask when they went out after catching a cold in control group but not in the case group,and 4 pairs of had the habit of wearing a mask when they went out after catching a cold in control group but no such habit in case group,and the OR value was 0.5.In the investigation of dietary habits,the comparison results of whether like cold vegetables,tea and parties showed that the OR values were all greater than 1.Conclusion:For infectious diseases,exposure history was the most important risk factor.In future studies,possible risk factors should be more comprehensively investigated.

1:4 case-control study on coronavirus disease 2019

Objective:To analyze the risk factors of COVID-19 infection in Danzhou,Hainan province.Methods:Case-control study was used,and the 1:4 control group of healthy residents(in Danzhou,Haikou,Beijing)were selected based on the matching conditions including same age and sex,age±2 years.The main contents of the questionnaire included living habits,dietary habits living environment,and exposure history.Results:There were 14 COVID-19 patients in Danzhou.And the control group included 56 residents from Danzhou,Haikou and Beijing.It was found that 85.7%(12/14)of the subjects in the case group exercise regularly.The exercise places were mainly community parks in Danzhou and Haikou,while mainly gyms or stadiums in Beijing.For dietary habits,control group in Beijing tended to using serving chopsticks when having dinner with family members or others than that in the case group(50.0%vs.21.4%,78.6%vs.35.7%).The results of exposure history showed that living in Wuhan or other city with cases reports in recent two months,contacting people who had living history in Wuhan or other city with cases reports in recent two months,and contacted people who confirmed COVID-19 infection or had symptoms recent two months were risk factors.Conclusion:For infectious diseases,exposure history was the most important risk factor.The influence of lifestyle differences may be smaller compared with exposure,and the individual specificity might lead to the infection-related factors difficult to found.In future studies,matching variables should be carefully selected in the case-control study of infectious diseases,and possible risk factors should be more comprehensively investigated.