Risk of COVID-19 is associated with long-term exposure to air pollution (preprint)

High risk of severe disease of COVID-19 has been associated with patients with chronic obstructive pulmonary disease, cardiovascular disease or hypertension, and long-term exposure to PM2.5 has been associated with COVID-19 mortality. We collate individual level data of confirmed COVID-19 cases during the first wave of the epidemic in mainland China by March 6, 2020. We pair these data with a mobile phone dataset, covering human movements from Wuhan before the travel ban and inner-city movements during the time of emergency response from 324 cities in China. Adjusting for socio-economic factors, an increase of 10 g/m3 in NO2 or PM2.5 was found to be associated with a 22.41% (95%CI: 7.28%-39.89%) or 15.35% (95%CI: 5.60%-25.98%) increase in the number of COVID-19 cases, and a 19.20% (95%CI: 4.03%-36.59%) or 9.61% (95%CI: 0.12%-20.01%) increase in severe infection, respectively. Our results highlight the importance of air quality improvements to health benefits.

Early evaluation of the Wuhan City travel restrictions in response to the 2019 novel coronavirus outbreak (preprint)

Respiratory illness caused by a novel coronavirus (COVID-19) appeared in China during December 2019. Attempting to contain infection, China banned travel to and from Wuhan city on 23 January and implemented a national emergency response. Here we evaluate the spread and control of the epidemic based on a unique synthesis of data including case reports, human movement and public health interventions. The Wuhan shutdown slowed the dispersal of infection to other cities by an estimated 2.91 days (95%CI: 2.54-3.29), delaying epidemic growth elsewhere in China. Other cities that implemented control measures pre-emptively reported 33.3% (11.1-44.4%) fewer cases in the first week of their outbreaks (13.0; 7.1-18.8) compared with cities that started control later (20.6; 14.5-26.8). Among interventions investigated here, the most effective were suspending intra-city public transport, closing entertainment venues and banning public gatherings. The national emergency response delayed the growth and limited the size of the COVID-19 epidemic and, by 19 February (day 50), had averted hundreds of thousands of cases across China.