[burger]

Interesting post on a virology forum (though posted by a virus scientist/statistician): it sounds like the paper reporting that there are two strains of the virus jumped to conclusions not supported by evidence:

However, they further claim that these two types have differing transmission rates: “Thus far, we found that, although the L type is derived from the S type, L (~70%) is more prevalent than S (~30%) among the sequenced SARS-CoV-2 genomes we examined. This pattern suggests that L has a higher transmission rate than the S type.” The abstract of the paper goes even further, stating outright that: “the S type, which is evolutionarily older and less aggressive…”

It is, however, important to appreciate that finding a majority of samples with a particular mutation is not evidence that viruses with that mutation transmit more readily. To make this claim would, at very minimum, require a comparison to be made to expectations under a null distribution assuming equal transmission rates. As this has not been performed by the authors, I believe there is insufficient evidence to make this suggestion, and that it is incorrect (and irresponsible) to state that there is any difference in transmission rates. Differences in the observed numbers of samples with and without this mutation are far more likely to be due to stochastic epidemiological effects.

tldr: there is no evidence for aggressive/non-aggressive strains

http://virological.org/t/response-to-on-...-cov-2/418

[burger]

Interesting post on a virology forum (though posted by a virus scientist/statistician): it sounds like the paper reporting that there are two strains of the virus jumped to conclusions not supported by evidence:

However, they further claim that these two types have differing transmission rates: “Thus far, we found that, although the L type is derived from the S type, L (~70%) is more prevalent than S (~30%) among the sequenced SARS-CoV-2 genomes we examined. This pattern suggests that L has a higher transmission rate than the S type.” The abstract of the paper goes even further, stating outright that: “the S type, which is evolutionarily older and less aggressive…”

It is, however, important to appreciate that finding a majority of samples with a particular mutation is not evidence that viruses with that mutation transmit more readily. To make this claim would, at very minimum, require a comparison to be made to expectations under a null distribution assuming equal transmission rates. As this has not been performed by the authors, I believe there is insufficient evidence to make this suggestion, and that it is incorrect (and irresponsible) to state that there is any difference in transmission rates. Differences in the observed numbers of samples with and without this mutation are far more likely to be due to stochastic epidemiological effects.

tldr: there is no evidence for aggressive/non-aggressive strains

http://virological.org/t/response-to-on-...-cov-2/418