Li Naizhe, Feng Yun, Vrancken Bram, Chen Yuyang, Dong Lu, Yang Qiqi, Kraemer Moritz U G, Pybus Oliver G, Zhang Hailin, Brady Oliver J, Tian Huaiyu
State Key Laboratory of Remote Sensing Science, Center for Global Change and Public Health, College of Global Change and Earth System Science, Beijing Normal University, Beijing, China.
College of Life Sciences, Beijing Normal University, Beijing, China.
Lancet Reg Health West Pac. 2021 Aug 20;14:100259. doi: 10.1016/j.lanwpc.2021.100259. eCollection 2021 Sep.
In response to the COVID-19 pandemic, China implemented strict restrictions on cross-border travel to prevent disease importation. Yunnan, a Chinese province that borders dengue-endemic countries in Southeast Asia, experienced unprecedented reduction in dengue, from 6840 recorded cases in 2019 to 260 in 2020.
Using a combination of epidemiological and virus genomic data, collected from 2013 to 2020 in Yunnan and neighbouring countries, we conduct a series of analyses to characterise the role of virus importation in driving dengue dynamics in Yunnan and assess the association between recent international travel restrictions and the decline in dengue reported in Yunnan in 2020.
We find strong evidence that dengue incidence between 2013-2019 in Yunnan was closely linked with international importation of cases. A 0-2 month lag in incidence not explained by seasonal differences, absence of local transmission in the winter, effective reproductive numbers < 1 (as estimated independently using genetic data) and diverse cosmopolitan dengue virus phylogenies all suggest dengue is non-endemic in Yunnan. Using a multivariate statistical model we show that the substantial decline in dengue incidence observed in Yunnan in 2020 but not in neighbouring countries is closely associated with the timing of international travel restrictions, even after accounting for other environmental drivers of dengue incidence.
We conclude that Yunnan is a regional sink for DENV lineage movement and that border restrictions may have substantially reduced dengue burden in 2020, potentially averting thousands of cases. Targeted testing and surveillance of travelers returning from high-risk areas could help to inform public health strategies to minimise or even eliminate dengue outbreaks in non-endemic settings like southern China.
Funding for this study was provided by National Key Research and Development Program of China, Beijing Science and Technology Planning Project (Z201100005420010); Beijing Natural Science Foundation (JQ18025); Beijing Advanced Innovation Program for Land Surface Science; National Natural Science Foundation of China (82073616); Young Elite Scientist Sponsorship Program by CAST (YESS) (2018QNRC001); H.T., O.P.G. and M.U.G.K. acknowledge support from the Oxford Martin School. O.J.B was supported by a Wellcome Trust Sir Henry Wellcome Fellowship (206471/Z/17/Z). Chinese translation of the abstract (Appendix 2).
为应对新冠疫情，中国实施了严格的跨境旅行限制措施以防止疾病输入。云南省与东南亚登革热流行国家接壤，该省登革热病例数出现了前所未有的下降，从2019年的6840例记录病例降至2020年的260例。
利用2013年至2020年在云南及周边国家收集的流行病学和病毒基因组数据相结合的方法，我们进行了一系列分析，以描述病毒输入在推动云南登革热动态变化中的作用，并评估近期国际旅行限制与2020年云南报告的登革热病例数下降之间的关联。
我们发现有力证据表明，2013 - 2019年云南的登革热发病率与病例的国际输入密切相关。发病率出现0 - 2个月的滞后（无法用季节差异解释）、冬季无本地传播、有效繁殖数<1（如使用基因数据独立估算）以及多种世界性登革热病毒系统发育情况均表明云南并非登革热地方性流行区。使用多变量统计模型我们表明，2020年在云南观察到的登革热发病率大幅下降而周边国家未出现这种情况，这与国际旅行限制的时间密切相关，即使在考虑了登革热发病率的其他环境驱动因素之后也是如此。
我们得出结论，云南是登革热病毒谱系传播的区域汇聚地，边境限制可能在2020年大幅减轻了登革热负担，有可能避免了数千例病例。对从高风险地区返回的旅行者进行针对性检测和监测，有助于为公共卫生策略提供信息，以尽量减少甚至消除中国南方等非地方性流行地区的登革热疫情爆发。
本研究的资金由中国国家重点研发计划、北京科技计划项目（Z201100005420010）；北京自然科学基金（JQ18025）；北京地表科学高级创新计划；中国国家自然科学基金（82073616）；中国科学技术协会青年人才托举工程（YESS）（2018QNRC001）提供；H.T.、O.P.G.和M.U.G.K.感谢牛津马丁学院的支持。O.J.B得到了惠康信托基金会亨利·惠康爵士奖学金（206471/Z/17/Z）的支持。摘要的中文翻译（附录2）。
