Many people speculate and even expect: Will COVID-19 disappear naturally as the temperature rises?
Let's stop speculating and listen to experts.
A few days ago, online preprint platform SSRN published a paper, and predicted the potential seasonality of COVID-19 by analyzing the temperature and latitude characteristics of COVID-19 epidemic.
The writer is from the Institute of Human Virus, University of Maryland School of Medicine, and the Interdisciplinary Center of Earth System Science, University of Maryland. At present, this paper has not been formally peer-reviewed.
Let's take a look at the findings of this foreign paper first, and then invite authoritative virologists in China to answer them.
Pattern: Distribution along the east-west direction, 30 to 50 degrees north latitude.
"Many infectious diseases, including human coronavirus, show seasonal characteristics." It is mentioned that human coronaviruses such as 229E, HKU 1, NL63 and OC43 usually cause common cold symptoms. It shows strong winter seasonality in February-April of 65438+, but it is difficult to detect in summer in temperate regions.
What is the relationship between COVID-19 epidemic worldwide and temperature and latitude? The author of this paper summarizes some laws.
"Due to geographical proximity and important travel links, the epidemiological model of the epidemic center predicts that Southeast Asia, especially Bangkok, will become the hardest hit area after Wuhan and China." The researchers wrote.
However, the development of the epidemic is not consistent with previous predictions. On the contrary, this paper points out that the community communication in COVID-19 presents a pattern of east-west distribution.
The article points out that the new epidemic center is generally within the range of 30 to 50 degrees north latitude.
South Korea, Japan, Iran and northern Italy have successively seen obvious epidemics. Since then, there have also been important community exchanges in the northwestern United States and France.
Global temperature map from October 20 18 165438 10 to March 20 19, in degrees Celsius. The black circle represents the area where major community transmission has occurred. Source: Climate Reanalyzer, Institute of Climate Change, University of Maine, USA.
Climate: the average temperature is 5- 1 1 degree, and the relative humidity is 47-79%.
"It is worth noting that, at the same time, the COVID-19 virus failed to spread to southern China countries. Compared with the above-mentioned milder areas, the number of cases and reported deaths in Southeast Asia is much less. " The researchers pointed out.
What are the rules of climate characteristics in those areas with obvious epidemic situation?
The researchers found that the average temperature and relative humidity in Wuhan, China in May 438+1October, 2020 were similar to those in other areas affected by the epidemic in February: the average temperature was between 5 and 1 1 Celsius, and the relative humidity was between 47% and 79%.
"These sites also show a * * * similarity, that is, the outbreak time coincides with the lowest point of the annual temperature cycle, so the temperature is relatively stable for more than a month." In addition, the researchers pointed out, the lowest temperature in cities that were not infected was below 0 degrees Celsius.
They also pointed out that the average temperature and relative humidity in the infected cities are similar to the laboratory conditions known to be conducive to the survival of coronavirus-the temperature is 4 degrees Celsius and the relative humidity is 20%-80%.
Global 2m temperature map from June 65438 +2020 10 to February 2020, in degrees Celsius. The white circle represents the area where major community communication has occurred. The red isoline marks the temperature range from 5 to 1 1 Celsius. The image is based on Copernicus Climate Change Service Information 2020.
Future: With the warming of the northern hemisphere, the risk of epidemic areas further north will increase.
The researchers believe that under this temperature condition, a new epidemic will break out for a long time, which may indicate that the risk of outbreak is increasing if it is in this temperature range for a long time.
However, the temperature in the infected cities has not dropped below 0 degrees Celsius, which indicates that there is a potential minimum temperature range. This avoids freeze-thaw cycles or other factors that may affect the viability of the virus.
"All these indicate that there is a potential direct relationship between the temperature in COVID-19 in 20 19 and the survival and diffusion of the environment." The researchers said.
Based on the above findings, the author predicts the spread of novel coronavirus in the next few weeks.
According to the temperature data in March and April last year, they predicted that the risk of community transmission of the epidemic would affect the area north of the current epidemic area. From east to west, these areas may include Northeast China, Central Asia, Eastern Europe, Central Europe, British Isles, Northeast America, Midwest and so on.
"In the next two months, the temperature in many parts of the northern hemisphere will rise sharply. However, with the rapid warming in the northern region, the temperature curves in these areas will soon overlap with those currently at risk. " The paper pointed out.
20191120201the average temperature and humidity of the community-spread cities and potential risk cities in COVID-19 from October to February. The data comes from worldweatheronline.com.
End: Summer may disappear or come back.
According to the seasonal characteristics of other human coronaviruses, the author predicts that in the next few months, the number of cases in COVID-19 may drop significantly in the epidemic areas above 30 degrees north latitude.
They put forward two possibilities:
One possibility is that COVID-19 is as low-grade as the flu in tropical areas, and it comes back in temperate regions in late autumn and early winter;
Another possibility is that in summer, COVID-19 can't survive and disappear in the tropics and the southern hemisphere.
It is worth noting that this paper does not consider climate anomalies, human intervention, virus variation and other factors.
"This means that although the current epidemic situation seems to have a strong correlation with latitude and temperature, the direct cause has not been confirmed, and the recent forecast is speculative and must be considered with extreme caution." The author of the paper stressed.
Global 2m temperature map from March to April in 20 19, in degrees Celsius. Green belt is an area where large-scale community communication may occur in the short term. Source: Climate Reanalyzer, Institute of Climate Change, University of Maine, USA.