Tracking progress towards malaria elimination in China: estimates of reproduction numbers and their spatiotemporal variation

Isobel Routledge; Shengjie Lai; Katherine E Battle; Azra C Ghani; Manuel Gomez-Rodriguez; Kyle B Gustafson; Swapnil Mishra; Joshua L Proctor; Andrew J Tatem; Zhongjie Li; Samir Bhatt

which is attributable to a seasonal or holiday effect. 134 as all data analysed was collected whilst the NMEP was in place, we cannot draw conclusions about 150 the impact of scaling back interventions or consider other counterfactuals. There is also some 151 uncertainty in our estimates of current and future , although the 95% credible intervals of these 152 estimates remain below 1. It is important to note that even with low values it is still possible for 153 locally-acquired cases to occur following importation, however the probability of sustained chains of 154 transmission decreases as decreases. There also is more uncertainty in our estimates of risk in 155 areas that have not observed many cases. It is difficult to determine whether an absence of cases is 156 due to a lack of detection, a lack of importation events occurring or a low underlying receptivity to 157 transmission. However, it is worth noting that the greatest uncertainty in our spatiotemporal risk 158 estimates of > 0 tends to be in areas of high elevation (elevation > 3000m), where there is 159 unlikely to be transmission. Given the large numbers of imported cases, it is important to highlight 160 . CC-BY-NC-ND 4.0 International license is made available under a The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. It in October and is associated with intranational travel to visit family. During this time, there is often 170 movement from cities to rural areas, and so in these contexts there may be more opportunities for 171 infection to occur as more people are exposed to bites from suitable vectors. This is supplemented 172 by our finding that these specific holidays are associated with small to moderate increases in , 173 however it is worth noting the very wide credible intervals and the great deal of uncertainty 174 associated with these estimates, and therefore caution is required when interpreting this finding. 175