Thousands of coronavirus cases prevented by China’s control interventions, analysis suggests

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On 31 December 2019 the first case of the novel coronavirus (COVID-19) was reported in Wuhan, China. Since then it has spread globally. Without an effective treatment or vaccination, non-pharmaceutical control interventions have been initiated worldwide.

Published in the Journal Science, a multi-institutional investigation has quantitatively analyzed how effective the implementation of non-pharmaceutical control mechanisms has been at limiting the spread of SARS-CoV-2 during the first 50 days of the epidemic in China.

“The number of confirmed cases in China by day 50 (19 February) of the epidemic was around 30,000” commented Christopher Dye (University of Oxford, UK). “Our analysis suggests that without the Wuhan travel ban and the national emergency response there would have been more than 700,000 confirmed COVID-19 cases outside of Wuhan by that date. China’s control measures appear to have worked by successfully breaking the chain of transmission – preventing contact between infectious and susceptible people.”

The investigation utilized case reports, human movement data – including cell phone mobility data – and public health information. By historically comparing the movements of 4.3 million people out of Wuhan, where the 50-day study period coincided with public holidays such as Spring Festival holiday and Chinese Lunar New Year, the team demonstrated that there was a significant reduction in movement following the travel ban on 23 January 2020.

“This delay provided extra time to prepare for the arrival of COVID-19 in more than 130 cities” stated Huaiyu Tian (Beijing Normal University, China).

The team noted there was a total of 262 cities reporting cases of COVID-19 within the first 28 days. This prompted many of the surrounding Chinese cities to also implement a Level 1 response, whereby public gatherings, entertainment venues, schools and public transport were prohibited.

The implementation of a Level 1 response resulted in a 33% reduction in the number of confirmed cases in the first few weeks of the outbreak, when compared with cities that did not implement this strategy. The research also demonstrates that these control measures effectively reduced the predicted number of cases in the first 50 days by 96%.

“Given the small fraction of the Chinese population that has been infected, a much larger number of people remains at risk of COVID-19” explained Tian. “We are acutely aware that resident or imported infections could lead to a resurgence of transmission.”

With many countries currently experiencing social isolation and restricted movement, this preliminary study provides initial data that non-pharmaceutical interventions are working to limit the spread of the virus. However, the threat of COVID-19 becoming endemic in the human population means pharmaceutical interventions will be required.

Sources: Tian H, Lui Y, Li Y et al. An investigation of transmission control measures during the first 50 days of the COVID-19 epidemic in China. Science. doi:10.1126/science.abb6105 (2020); www.oxfordmartin.ox.ac.uk/news/china-prevented-700-000-covid-19-cases/

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