Abstract:
Background Although associations between key weather indicators (i.e. temperature and humidity) and COVID-19 mortality have been reported, the relationship between these exposures at different timings in early infection stages (from virus exposure up to a few days after symptom onset) and the probability of death after infection (also called case fatality rate, CFR) has yet to be determined. Methods We estimated the instantaneous CFR of eight European countries using Bayesian inference in conjunction with stochastic transmission models, taking account of delays in reporting the number of newly confirmed cases and deaths. The exposure-lag-response associations between fatality rate and weather conditions to which patients were exposed at different timings were obtained using distributed lag nonlinear models coupled with mixed-effect models. Results Our results show that the Odds Ratio (OR) of death is negatively associated with the temperature, with two maxima (OR = 1.29 (95% CI: 1.23, 1.35) at -0.1°C; OR = 1.12 (95% CI: 1.08, 1.16) at 0.1°C) occurring at the time of virus exposure and after symptom onset. Two minima (OR = 0.81 (95% CI: 0.71, 0.92) at 23.2°C; OR = 0.71 (95% CI: 0.63, 0.80) at 21.7°C) also occurred at these two distinct periods correspondingly. Low humidity (below 50%) during the early stages and high humidity (approximately 89%) after symptom onset were related to the lower fatality. Conclusion Environmental conditions may affect not only the initial viral load when patients are exposed to the virus, but also individuals\' immune response around symptom onset. Warmer temperatures and higher humidity after symptom onset were linked to lower fatality.
摘要:
背景技术尽管已经报道了关键天气指标(即温度和湿度)与COVID-19死亡率之间的关联,感染早期不同时间的这些暴露(从病毒暴露到症状发作后几天)与感染后死亡的可能性(也称为病死率,CFR)尚未确定。方法我们使用贝叶斯推断结合随机传输模型估计了八个欧洲国家的瞬时CFR,考虑到延迟报告新确诊病例和死亡人数。使用分布滞后非线性模型和混合效应模型,获得了死亡率与患者在不同时间暴露的天气条件之间的暴露滞后反应关联。结果我们的结果表明,死亡的几率(OR)与温度呈负相关,在病毒暴露时和症状发作后出现两个最大值(-0.1°C时OR=1.29(95%CI:1.23,1.35);0.1°C时OR=1.12(95%CI:1.08,1.16))。两个最小值(在23.2°C时OR=0.81(95%CI:0.71,0.92);在21.7°C时OR=0.71(95%CI:0.63,0.80))也发生在这两个不同的时期。早期的低湿度(低于50%)和症状发作后的高湿度(约89%)与较低的死亡率有关。结论环境条件可能不仅影响患者接触病毒时的初始病毒载量,而且个体在症状发作周围的免疫反应。症状发作后温度升高和湿度升高与死亡率降低有关。