key: cord-1039674-jd4rjbpt authors: Song, Shujuan; Kong, Qingxin; Huang, Chunping; Yang, Xuhui; Liu, Muwen; Kao, Qingjun; Sun, Zhou; Wang, Jing title: Re: ‘Non-pharmaceutical intervention strategies for outbreak of COVID-19 in Hangzhou, China’ date: 2020-07-28 journal: Public Health DOI: 10.1016/j.puhe.2020.07.026 sha: 74b7a5366c292df21f5b2c58d572de093ed50e60 doc_id: 1039674 cord_uid: jd4rjbpt Abstract In this letter, we try to evaluate the science behind the strategies mentioned in Kong's letter "Non-pharmaceutical intervention strategies for outbreak of COVID-19 in Hangzhou, China", by retrospective analysis of case-control method. Comparing with no clear contact with confirmed cases, morbidity rate of patients that has had close contacts with confirmed cases was 66.09 times higher and patients who have had travelled to Wuhan (high risk area) was 6.58 times higher.These results fully illustrated the importance of case isolation and close contacts management, which were implemented at all stages according to Kong et al. Kong et al. [12] stated that a large-scale outbreak of coronavirus disease 2019 (COVID-19), with 169 confirmed cases, was quickly controlled by non-pharmaceutical interventions in approximately 6 weeks, and that the intervention strategies could be helpful to other countries experiencing the COVID-19 pandemic. However, as Kong et al. [12] mentioned, the interventions implemented lacked strong scientific basis and effective evaluation. In this letter, we try to evaluate the science behind these strategies by retrospective analysis of case-control method. The core intervention strategy in Hangzhou was to adopt the corresponding isolation strategies at different stages of the COVID-19 epidemic: namely, isolation of patients or suspected patients and quarantine of close contacts at the early stage of the epidemic, followed by community-wide containment after the disease started to spread locally. Hence, our research focused on key factors such as exposure history, confirmed close contact, travelling to high risk areas and living in the same community as a confirmed case. In addition, we considered patient age and living region (urban or suburban), which could have an impact on the analysis of results. In our research, up to 31 May 2020, 200 confirmed COVID-19 patients (including 19 asymptomatic cases) were selected (case group) in addition to 588 excluded cases of suspected patients (control group). The difference in COVID-19 morbidity rate between the case group and control group was analysed using an unconditional logistic regression model. The results showed that COVID-19 morbidity risk increased with age, and that the risk was higher for individuals living in suburban areas than urban areas. After controlling for age and region variables, exposure history stood out as a risk factor. The morbidity rate of patients who had close contact with confirmed cases was 66.09 times higher than individuals who had no clear contact with confirmed cases. In addition, the morbidity rate of patients who had travelled to Wuhan (high risk area) was 6.58 times higher than those who had not travelled to Wuhan (see Table 1 ). These results fully illustrate the importance of case isolation and close contact management (i.e. quarantine), which were implemented at all stages of the epidemic, according to Kong et al. [12] The earlier the confirmed cases were located, and the stricter the management of close contacts and personnel with a history of exposure in key areas, the better the prevention control effect of the epidemic. Similar results have been seen in Singapore, Hong Kong and other places [1] [2] [3] . According to our results, living in the same community as a confirmed case is not a risk factor; however, community-wide containment should not be deemed as unnecessary. In Hangzhou, more than 5000 close contacts were placed in to quarantine [4] , more than 400,000 nucleic acid tests were conducted between April 8 and June 1 [5] , and more than 21 million (including the floating population) people used the health code declaration through their smart phones up to May 15 [6] . We believe that effective case isolation and close contact quarantine in Hangzhou are the main reasons that living in the same community with confirmed cases was not a risk factor. Community control, as implemented during the second stage of the epidemic in Hangzhou, is still very necessary in countries with widespread community transmission. Community-wide containment is particularly important when case isolation and close-contact quarantine cannot be achieved, when extensive testing cannot be carried out in the community [7] [8] [9] and when there is no sensitive surveillance system available (including hospital and community monitoring). Furthermore, we discovered a significant difference in risk between urban and suburban areas. Individuals in the case group were mainly living in suburban areas, whereas the control group population were mainly from urban areas. The reason behind the difference may be due to a gap between urban and suburban/rural areas in terms of health resources, personal health literacy and supportive environment. Individuals living in urban areas have relatively more abundant health resources, are more sensitive to health hazards and have a relatively higher degree of concern for their own well-being. In general, individuals in urban areas have healthier preventative behaviours, such as actively and correctly wearing face masks and more frequent hand washing. They are also more likely to go to the hospital for treatment and corresponding screening if COVID-19 symptoms developed. According to the health literacy monitoring data of Hangzhou residents in 2019, there is a significant gap between urban and rural residents' health literacy [10] . Knowledge and skills of protection from respiratory infectious diseases greatly impacts the probability of infection [11] . It is evident that health resources, personal health literacy and health support environment have a great impact on COVID-19 infection and diagnosis. Therefore, these factors should be considered in the prevention and control strategy to develop more appropriate prevention for different regions. Not required (data collection and analysis of cases and close contacts were *P value < 0.05, **P value < 0.01, ***P value < 0.001. Interrupting transmission of COVID-19: lessons from containment efforts in Singapore Impact assessment of non-pharmaceutical interventions against coronavirus disease 2019 and influenza in Hong Kong: an observational study COVID-19: Learning from lessons to guide treatment and prevention interventions. mSphere Risk of SARS-CoV-2 infection among contacts of individuals with COVID-19 in Hangzhou Zhejiang will continue to increase the detection of nucleic acid in new coronary pneumonia virus 21.24 million health codes have been issued in Hangzhou The global community needs to swiftly ramp up the response to contain COVID-19 Coronavirus disease (COVID-19) community testing team in Scotland: a 14-day review Effect of non-pharmaceutical interventions to contain COVID-19 in China Hangzhou Municipal Health Commission. How is the health literacy level of Hangzhou citizens in Applying Principles of Behaviour Change to Reduce SARS-CoV-2 Transmission Non-pharmaceutical intervention strategies for outbreak of COVID-19 in Hangzhou Table 1 Unconditional logistic regression analysis of risk factors for COVID-19 cases in Hangzhou None declared.