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▎The content team editor of WuXi AppTec yesterday, a paper published in the top academic journal "Science" pointed out that compared with patients whose condition is severe enough to require hospitalization, those patients with COVID-19 who have not yet developed symptoms, are asymptomatic, or have mild symptoms can have the same Level of virus transmission capacity.
This research has given us a new understanding of the spread of the new coronavirus, and it has shown that these symptoms are not obvious, and seemingly healthy individuals may be the key to triggering an outbreak in the community, which has important guiding significance for prevention and control.
The significance of assessing and quantifying the ability of the virus to spread is self-evident for epidemic prevention and control.
According to the introduction in the press release of the paper, R0 is a term that is often mentioned.
It shows how many healthy people can be infected by a patient with a new crown infection on average.
But R0 is more of an epidemiological concept, and it cannot assess the risk of infection at the individual level.
In order to better understand this, a scientific research team led by German scientists analyzed PCR samples from more than 25,000 new crown cases to assess the viral load of these patients at the time of testing (such as the throat).
At the same time, the researchers also referred to the minimum viral load that can successfully isolate the new coronavirus in cell culture.
Using these data, the researchers reconstructed a model of the change in viral load with the time of infection, covering different age groups, different disease severity, and different virus variants.
▲The research team measured the viral load of samples from more than 25,000 COVID-19 patients (picture source: reference [2]; Credit: Charité | Victor Corman).
The most important findings came from the analysis of people with different symptoms.
Researchers found that there was no significant difference in viral load among adults aged 20-65, with an average throat swab containing 2.
5 million copies of the virus.However, about 9% of COVID-19 cases have a very high viral load, and there are about 1 billion copies of the virus in the sample, which is theoretically extremely infectious.
What is puzzling is that more than one-third of these patients with extremely high viral loads have no symptoms or very mild symptoms! Researchers believe that these few cases may be the source of a large number of infections.
"Many people have no symptoms.
This fact emphasizes the importance of social distancing and mandatory wearing of masks and other epidemic control measures.
" said Professor Christian Drosten, the corresponding author of this study.
Image source: 123RF Another important discovery comes from the B.
1.
1.
7 variant virus that appeared in the United Kingdom.
The viral load of patients infected with this virus is an order of magnitude higher.
Laboratory data shows that its infectivity has increased by 2.
6 times.
"One thing can be confirmed," Professor Drosten commented, "B.
1.
1.
7 is more contagious than other variants.
" The researchers also made some other findings.
For example, children aged 0-5 have the lowest virus copy number, about 800,000 copies.
In people aged 5-20, the viral load increases with age.
However, the researchers also pointed out that the sampling methods for children and adults are different, and fewer samples may be obtained.
If these differences are taken into account, the researchers pointed out that even if children and adults have the same level of viral load, PCR results will appear to be even less, so interpreting this result requires caution.
And although the number of copies of the virus in children is less than one-third of that of adults, scientists estimate that the infectivity of children is only 20% lower than that of adult patients, indicating that viral load and transmission are not simply proportional.
Professor Drosten also pointed out that these findings and other studies have shown that the infectivity of different age groups is roughly at the same level.
The graphics researchers of WuXi AppTec's content team made a summary at the end of the paper.
They said that patients with no symptoms, asymptomatics, and mild symptoms are expected to have the same infectious ability as hospitalized patients.
Based on these findings, the researchers pointed out that in addition to drug intervention, social isolation and masks are still the key to preventing future outbreaks.
As long as the virus exists, we should take these measures for all age groups.
Reference: [1] Terry C.
Jones, et al.
, (2021), Estimating infectiousness throughout SARS-CoV-2 infection course, Science, DOI: 10.
1126/science.
abi5273[2] SARS-CoV-2: Estimating infectiousness , Retrieved May 25, 2021, from
This research has given us a new understanding of the spread of the new coronavirus, and it has shown that these symptoms are not obvious, and seemingly healthy individuals may be the key to triggering an outbreak in the community, which has important guiding significance for prevention and control.
The significance of assessing and quantifying the ability of the virus to spread is self-evident for epidemic prevention and control.
According to the introduction in the press release of the paper, R0 is a term that is often mentioned.
It shows how many healthy people can be infected by a patient with a new crown infection on average.
But R0 is more of an epidemiological concept, and it cannot assess the risk of infection at the individual level.
In order to better understand this, a scientific research team led by German scientists analyzed PCR samples from more than 25,000 new crown cases to assess the viral load of these patients at the time of testing (such as the throat).
At the same time, the researchers also referred to the minimum viral load that can successfully isolate the new coronavirus in cell culture.
Using these data, the researchers reconstructed a model of the change in viral load with the time of infection, covering different age groups, different disease severity, and different virus variants.
▲The research team measured the viral load of samples from more than 25,000 COVID-19 patients (picture source: reference [2]; Credit: Charité | Victor Corman).
The most important findings came from the analysis of people with different symptoms.
Researchers found that there was no significant difference in viral load among adults aged 20-65, with an average throat swab containing 2.
5 million copies of the virus.However, about 9% of COVID-19 cases have a very high viral load, and there are about 1 billion copies of the virus in the sample, which is theoretically extremely infectious.
What is puzzling is that more than one-third of these patients with extremely high viral loads have no symptoms or very mild symptoms! Researchers believe that these few cases may be the source of a large number of infections.
"Many people have no symptoms.
This fact emphasizes the importance of social distancing and mandatory wearing of masks and other epidemic control measures.
" said Professor Christian Drosten, the corresponding author of this study.
Image source: 123RF Another important discovery comes from the B.
1.
1.
7 variant virus that appeared in the United Kingdom.
The viral load of patients infected with this virus is an order of magnitude higher.
Laboratory data shows that its infectivity has increased by 2.
6 times.
"One thing can be confirmed," Professor Drosten commented, "B.
1.
1.
7 is more contagious than other variants.
" The researchers also made some other findings.
For example, children aged 0-5 have the lowest virus copy number, about 800,000 copies.
In people aged 5-20, the viral load increases with age.
However, the researchers also pointed out that the sampling methods for children and adults are different, and fewer samples may be obtained.
If these differences are taken into account, the researchers pointed out that even if children and adults have the same level of viral load, PCR results will appear to be even less, so interpreting this result requires caution.
And although the number of copies of the virus in children is less than one-third of that of adults, scientists estimate that the infectivity of children is only 20% lower than that of adult patients, indicating that viral load and transmission are not simply proportional.
Professor Drosten also pointed out that these findings and other studies have shown that the infectivity of different age groups is roughly at the same level.
The graphics researchers of WuXi AppTec's content team made a summary at the end of the paper.
They said that patients with no symptoms, asymptomatics, and mild symptoms are expected to have the same infectious ability as hospitalized patients.
Based on these findings, the researchers pointed out that in addition to drug intervention, social isolation and masks are still the key to preventing future outbreaks.
As long as the virus exists, we should take these measures for all age groups.
Reference: [1] Terry C.
Jones, et al.
, (2021), Estimating infectiousness throughout SARS-CoV-2 infection course, Science, DOI: 10.
1126/science.
abi5273[2] SARS-CoV-2: Estimating infectiousness , Retrieved May 25, 2021, from
