Heidelberg Institute of Global Health, Heidelberg University Medical School, Heidelberg University, Heidelberg, Germany.
Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
Sci Rep. 2021 Apr 27;11(1):9042. doi: 10.1038/s41598-021-87692-z.
Visual inspection of world maps shows that coronavirus disease 2019 (COVID-19) is less prevalent in countries closer to the equator, where heat and humidity tend to be higher. Scientists disagree how to interpret this observation because the relationship between COVID-19 and climatic conditions may be confounded by many factors. We regress the logarithm of confirmed COVID-19 cases per million inhabitants in a country against the country's distance from the equator, controlling for key confounding factors: air travel, vehicle concentration, urbanization, COVID-19 testing intensity, cell phone usage, income, old-age dependency ratio, and health expenditure. A one-degree increase in absolute latitude is associated with a 4.3% increase in cases per million inhabitants as of January 9, 2021 (p value < 0.001). Our results imply that a country, which is located 1000 km closer to the equator, could expect 33% fewer cases per million inhabitants. Since the change in Earth's angle towards the sun between equinox and solstice is about 23.5°, one could expect a difference in cases per million inhabitants of 64% between two hypothetical countries whose climates differ to a similar extent as two adjacent seasons. According to our results, countries are expected to see a decline in new COVID-19 cases during summer and a resurgence during winter. However, our results do not imply that the disease will vanish during summer or will not affect countries close to the equator. Rather, the higher temperatures and more intense UV radiation in summer are likely to support public health measures to contain SARS-CoV-2.
从世界地图上可以直观地看出，靠近赤道的国家 2019 冠状病毒病（COVID-19）的发病率较低，这些地区往往高温高湿。科学家们对这一观察结果的解释存在分歧，因为 COVID-19 与气候条件之间的关系可能受到许多因素的影响。我们对各国每百万居民中已确诊的 COVID-19 病例数的对数值与各国距赤道的距离进行回归，同时控制了以下关键混淆因素：航空旅行、车辆密度、城市化、COVID-19 检测强度、手机使用量、收入、老年抚养比和卫生支出。截至 2021 年 1 月 9 日，绝对纬度每增加一度，每百万居民中的病例数就会增加 4.3%（p 值<0.001）。我们的研究结果表明，一个国家如果距离赤道近 1000 公里，那么其每百万居民中的病例数可能会减少 33%。由于地球与太阳之间的夹角在春分和夏至之间的变化约为 23.5°，因此可以预计，在两个假设的国家中，气候差异与两个相邻季节相似的国家之间，每百万居民中的病例数差异将达到 64%。根据我们的研究结果，各国预计在夏季新的 COVID-19 病例数量将会减少，而在冬季病例数量将会增加。然而，我们的研究结果并不意味着这种疾病在夏季会消失，或者不会影响靠近赤道的国家。相反，夏季较高的温度和更强的紫外线辐射可能会支持采取公共卫生措施来控制 SARS-CoV-2。
