《科学》杂志：中国“封城”的决定可能阻止了数十万病例的出现
为了防止新冠肺炎疫情更大规模地在全国范围内扩散，1月23日，中国做出了武汉“封城”的决定。
这场针对整座城市的“隔离”，以及中国其他省市及时响应的防控措施，起到了怎样的效果呢？
当地时间 3 月 31 日，《科学》杂志在线发表的一项研究认为，自 1 月 23 日起实行的封城等措施让中国新冠肺炎感染者的总病例数减少了 96%，可能阻止了超过70万病例的出现，对疫情的遏制起到了至关重要的作用。
China's decision to lock down the city of Wuhan may have prevented more than 700,000 COVID-19 cases by containing the spread of the coronavirus, according to a study published in the journal Science on Tuesday.
这项研究题为“对中国 COVID-19 疫情暴发的最初 50 天内传播控制措施的调查”由22 位科学家联合完成，他们来自中国、美国和英国的 15 家机构 。
Drastic Chinese control measures in the first 50 days of the epidemic bought other cities across the country valuable time to prepare and install their own restrictions, says the paper authored by researchers from China, the United States and the UK.
A motorcyclist rides across a bridge in Wuhan, central China's Hubei Province, January 25, 2020. /AP
研究人员表示，截至 2 月 19 日，也就是疫情首次公开通报后的第 50 天，中国已有30,000例确诊病例。而如果没有武汉的出行禁令和中国各省市的紧急应对措施重大突发公共卫生事件一级响应，武汉以外可能会出现超过70万例的疫情暴发。
By day 50 of the epidemic - February 19 - there were 30,000 confirmed cases in China, said Oxford fellow Christopher Dye, one of the paper's authors.
"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," he was quoted as saying in a press release.
"China's control measures appear to have worked by successfully breaking the chain of transmission – preventing contact between infectious and susceptible people."
研究人员试图结合病例报告，公共卫生信息和手机位置跟踪功能来研究病毒的传播，并探讨人类活动的作用、旅行限制和社会距离措施在预防传染病传播方面的有效性。
The researchers used a combination of case reports, public health information and mobile phone location tracking to investigate the spread of the virus.
The phone tracking provided a "fascinating" new stream of data, said another of the report's authors, Penn State biology professor Ottar Bjornstad.
该研究的时段覆盖了40天的春运，即1月25日春节的前15天，以及之后的25天。研究人员运用获得的手机位置数据将2020年的出行情况与前几年进行了比较，以比对假期出行对中国各地传播感染的影响。
数据显示，2017年和2018年两年在中国农历新年前的15天里，平均有520万人从武汉流出；农历新年后的25天里，每年平均有670万人流出。而在2020年的春运期间，虽然禁令发布前有430万人已经离开了武汉，但春节后的25天时间里，禁令几乎阻止了所有出行活动。
The time period they studied encompassed China's biggest holiday, the Chinese New Year.
The researchers "were able to compare patterns of travel into and out of Wuhan during the outbreak with cell phone data from two previous spring festivals," Bjornstad said.
"The analysis revealed an extraordinary reduction in movement following the travel ban of January 23, 2020. Based on this data, we could also calculate the likely reduction in Wuhan-associated cases in other cities across China."
这项研究的模型显示，武汉的出行禁令推迟了新冠病毒在其他城市的传播。
从研究数据来看，武汉的出行禁令将COVID-19在其他城市的暴发时间平均推迟了2.91天（95%CI: 2.54-3.29天），从而使这些城市有时间通过禁止公共聚会和关闭娱乐场所等方式进行防控准备。全国有超过130个城市受益于这一推迟，这些城市覆盖了中国一半以上的地理面积和人口。
The Wuhan shutdown delayed the arrival of the virus in other cities, their model showed, giving them time to prepare by banning public gatherings and closing entertainment venues, among other measures.
两个月前，对于武汉的出行禁令被全世界视为这场战“疫”的戏剧性升级。但目前，世界上已有近半人口被要求呆在家里，许多疫情严峻的国家也开始考虑将“封城”用作控制疫情的必要手段。
4月8日，武汉即将迎来“解封”，疫情防控的下一步是什么，是中国和其他一些国家要认真思考的。
Nearly half of humanity has now been told to stay home to curb the spread of the virus, and lockdowns are rapidly becoming normalized.
But when Beijing first shut down Wuhan more than two months ago, the decision was seen as a dramatic escalation in the fight against infection.
With the restrictions in the city slowly being lifted and life inching closer to normal, the question for China and other countries around the globe is what will happen once movement resumes.