I wonder how many people remember how SARS began in 2003?
At the end of 2002, Huang Xingchu, a chef at a restaurant in Shenzhen, suddenly felt very uncomfortable, and he had symptoms of fever and cold, and his condition did not improve after several treatments.
After the condition deteriorated many times, Huang Xingchu was transferred to Heyuan People's Hospital for treatment, but even in a large hospital with more complete medical facilities, Huang Xingchu's condition was not controlled, the high fever once reached 40 ° C, breathing difficulties, and even words could not be spoken, and finally could only be transferred to the hospital again.
Photo note: Huang Xingchu Source: Guangzhou Daily
At the time of the second transfer to the hospital, Huang Xingchu was reported by the media as "the world's first case of SARS patient being hospitalized".
After more than a month of treatment, Huang Xingchu's body recovered, but the doctors who had been in close contact with him were infected with the SARS virus (or SARS virus).
Because Huang Xingchu was the first reported case of SARS patients, he received some criticism, in fact, there were infected people before him, and now the first person officially identified is Pang Zuoyao.
Regardless of the cause of SARS, the outbreak did not last long, starting with Huang Xingchu being reported as the first infected person on December 15, 2002, and ending the outbreak in July 2003, when the World Health Organization declared the outbreak over.
Note: Coronavirus under a microscope
The SARS virus is also a coronavirus, and it is closely related to the new coronavirus that created the pandemic, and the two are similar in both transmission routes and pathogenic principles.
So the question is, why does the SARS virus disappear so quickly that it doesn't even need to be vaccinated, and the new crown virus has been spreading for more than two years since it was reported at the end of 2019?
The SARS virus is more deadly than the new crown
Coronaviruses are RNA viruses, and SARS viruses and new coronaviruses have more than 80% identical RNA genomes, which is very, very similar to rapidly mutating RNA viruses.
In fact, these two viruses are the closest of the coronaviruses that infect humans, and they are likely to have similar or common ancestors (the origin of the new coronavirus is unknown), which is reflected in the naming of the two - SARS-CoV-1 (SARS virus) and SARS-CoV-2 (new coronavirus).
Because of this, the proteins on the outer surface of the two viruses are also very similar, and they also use the same receptors on the surface of our cells to enter human cells, and the infections of the two viruses are mostly concentrated in the lungs.
But there are also many differences between the two viruses, the most obvious of which can be said in terms of data is that the SARS virus is more deadly than this new coronavirus.
From the beginning to the end of the SARS virus, there are more than 8,000 infected people, about 700 deaths, nearly 10% mortality, and the cumulative confirmed diagnosis of the new crown virus has reached more than 300 million people, with a case fatality rate of about 1.7%.
Although the number of infected people of the two viruses is tens of thousands of times different, in fact, the basic number of infections (R0 value) of the two is similar, the R0 value of the SARS virus is between 2-3 (referring to the average 2-3 people who can infect 1 person), and the R0 value of the new coronavirus is also around 2.5.
Isn't that weird? The basic number of infections of the two viruses is similar, why is the result of transmission so different?
The answer is that the coronavirus is more successful than the SARS virus!
This success is reflected in several ways, and these successful performances are also the reason why the new crown virus is not so easy to disappear.
Why is it easier for covid-19 to disappear?
First, more deadly viruses are actually more failed evolutions, because if the host is killed, the virus naturally cannot survive.
The difference between the two, source: News Medical
SarS virus is not only more deadly than the new crown virus, but also people infected with it will quickly enter a high-risk state and be hospitalized, statistics show that more than 70% of SARS infected people need to be hospitalized, while the new crown virus is only about 20%.
This virus, which is prone to high-risk diseases, is actually easier to control its spread, because as long as it appears, it must be hospitalized, which makes it easy to take isolation work and reduce the risk of infection continued transmission.
Second, the incubation period of the new crown virus is longer, and it is also contagious during the incubation period.
For the SARS virus, its incubation period is 2-7 days, but most people will have a high-risk disease on the third day, which can be detected and treated early.
In addition, the SARS virus is very weak in the incubation period, so Huang Xingchu was infected by medical staff who were in close contact with him at high risk, not others.
The incubation period of the new crown virus is 1-14 days (so the quarantine time is two weeks), during which it also has a strong contagious capacity, coupled with a variety of asymptomatic patients, making it particularly difficult to control the epidemic.
Note: Survival comparison between the two viruses, News Medical
Third, the viability of the new crown virus is stronger than that of the SARS virus.
Studies have shown that in most environments (environments where we may be exposed to and spread the virus), the viability of the two viruses is similar, except for "cardboard", the SARS virus died after about 8 hours on the cardboard, while the new crown virus can still find live virus after 72 hours.
Most importantly, the survival ability of the SARS virus to survive at high temperatures is very obvious, for example, at 38 degrees Celsius and 95% humidity, its infectivity will be significantly reduced, so in the summer of 2003, SARS suddenly disappeared.
The reason for the sudden disappearance of the SARS virus is not clear, but it is certain that it did not perform as well as the new crown virus in the above three aspects, so it disappeared quickly.
And the new crown virus because it is more hidden, more survivable, become easier to spread, when the virus is easier to spread, it will be difficult to control, because it is easy to "replace", just like the new crown virus will appear every few months a powerful new strain.
Photo note: Fighting the SARS hero group eagle
At last
In fact, the SARS virus has developed a vaccine, but it has just undergone animal experiments, and before it has time to inoculate people, the virus has disappeared on its own.
A typical feature of viruses is that they appear suddenly like the SARS virus and then disappear without warning.
So, these two years are difficult, but I believe it will soon pass.
Resources:
Lois Zoppi.How does SARS-CoV-2 Compare to SARS-CoV?. News Medical
Source: Strange Luo
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