The Asahi Shimbun:

There are many papers on the mutation of the virus. According to a paper that was published by an expert Chinese team, there are two subtypes of the virus. One is an older S subtype, and the other is an L subtype that is more infectious. Which one do you think is mutating? Is there any new mutation of the virus? Do you think the virus has the same virulence and is equally contagious in other countries? Thank you.

Liu Peipei:

Different research teams around the world have suggested various methods for typing and subtyping viruses, and the method of subtyping S and L is just one of them. Regarding this method, you will understand after you finish reading the paper, as the author has attached an explanation that has clearly explained there is no evidence about any direct relation between the virulence of the virus and these two subtypes.  

Jin Qi:

I would like to add something more in terms of the aspect that Dr. Liu has mentioned. If my memory serves me right, this paper was published at the very early stages of the COVID-19 outbreak. From a scientific perspective, having enough strains available is a prerequisite for any evolutionary analysis of the virus. However, that paper was published very early on, and researchers had only obtained 100 or 200 strains for the analysis. But up to now, how many strains are there in the public database? I believe the media must know well of the number. Moreover, given the same data, different statistical methods and algorithms will lead to different results, and this has been widely recognized in the field of evolutionary analysis. Consequently, different papers, in terms of their results or assumptions, can be explained from different perspectives. I, personally, believe that this paper currently shows some limitations in terms of the number of virus strains and locations affected by the virus, as the virus had just occurred in some regions at that moment. But now the pandemic has swept the world, including Europe and America, so you can get more strains at different times and from various locations, and the results will accordingly be more accurate. When we look at the paper right now, we may interpret it in a different way. I think that with the large increase in the number of virus strains in the public database, the results of papers published in the future will be more accurate and precise. Thank you.  

Wang Guiqiang:

I agree with Mr. Jin. First, the mutation of pathogenic microorganisms is a very normal phenomenon. After mutations, you need a lot of data to prove whether a strain variation can be defined as a subtype. Hepatitis B has different genotypes, as well as different subtypes, and there are basic definitions for them. I'm also aware of this paper. As to whether the mutations mentioned in the paper can be defined as subtypes, the author later corrected his conclusion and called them lineages — not subtypes. This is because to define a mutation as a subtype, you need to have a large number of virus strains to make comparisons and find out those variation sequences; then you can determine whether to call it a subtype or not.  

Second, these two lineages are not directly related to the virulence or the contagion of the virus, which was also pointed out by the author of the paper. Of course, we cannot rule out the possibility that some variations may become more contagious, which is possible, but we need more samples to prove that. Thank you. 

Yan Jinghua:

The relations between mutations and pathogenicity rate and contagion, from a biological perspective, must go through sequence analysis and bioinformatics analysis, and the final results must be verified from a biological perspective. For example, a mutation of a virus, according to epidemiology or animal models, does have increased infection or virulence. This is my point of view. Thank you.