A newly published analysis of 32,583 laboratory-confirmed COVID-19 cases in Wuhan, China sheds light on the epidemiological characteristics of the disease and shows that numerous non-pharmaceutical interventions, including social distancing, centralized isolation and quarantine, and a door-to-door universal symptom survey, in conjunction with early treatment efforts, substantially slowed its spread.
The research, co-led by Xihong Lin, professor of biostatistics at Harvard T.H. Chan School of Public Health and professor of statistics at Harvard Faculty of Arts and Sciences, was published in JAMA on April 10, 2020. The findings build on Lin and colleagues’ previous research of COVID-19 in Wuhan, and the study was conducted in collaboration with Tongji School of Public Health of Huazhong University of Science and Technology and Fudan University.
To analyze the impact of various non-pharmaceutical interventions on the spread of COVID-19 in Wuhan, the research team segmented the data into five periods of time: before January 10, when no interventions were in place; January 10-22, when there were large numbers of people moving about for the Chinese New Year holiday; January 23-February 1, when several social distancing interventions were implemented, including traffic restrictions and home quarantine; February 2-16, when intensified isolation and quarantine measures, referred to as “centralized quarantine,” were further implemented, including centralized isolation and treatment of infected patients, including mild and moderate patients, and centralized quarantine of symptomatic subjects and close contacts of infected patients; and February 17-March 8, when a universal community screening for symptoms was further added.
The findings showed that the rate of new cases peaked in the third period and then declined as multi-pronged prevention and control efforts were intensified and implemented, including both social distancing, which helps reduce community transmission, and centralized quarantine policy, which helps reduce disease transmission among family members within households, and was most common.
For centralized quarantine, all confirmed cases were placed into designated hospitals or health facilities for treatment, and suspected cases—those with a fever or other symptoms of COVID-—and close contacts of confirmed cases were quarantined in designated facilities, such as hotels and university dorms. In those settings,small children stayed in the same private rooms as parents, while older children had their own private rooms. These multi-faceted interventions led to a steep drop in new cases and disease transmission. In particular, the study showed that the estimated R value, or the average number of people infected by one infected person, dropped from higher than 3 before the interventions to as low as 0.1 after the full scope of interventions was implemented.
The study also offered new insights into the demographics of the Wuhan epidemic. It showed that the median patient age was 56.7 years and 51.6% of patients were women. Moreover, the study showed that elder people had the highest risk for infection and severe disease, while children were at a substantially lower risk of infection. Infants, however, had a much higher risk of infection compared with other children. Women were at a statistically significant lower risk for severe disease compared with men. The study also showed that health care workers were at a substantially higher risk of infection when compared with the general population when not protected by PPE.
An accompanying editorial described the study as “remarkable in several ways” and said that it “hints at a tantalizing possibility: the accessibility of data to support the real-time formative evaluation of public health interventions in an ongoing pandemic.”