Hong Kong's first genomic study of the virus reveals lower virulence than European and US strains 

In Europe, the United States and other areas, Wuhan pneumonia has infected around 800,000 people and killed at least 80,000. These figures and ratios [to their respective populations] far surpass those of Hong Kong, which could be due to genetic mutation within the virus. A recent study* by the Hong Kong Polytechnic University (PolyU) showed that none of the 50 patients in the first month of the outbreak carried the P314L mutation commonly seen in Europe and the United States. Instead, nearly 90% of patients had the G251V mutation. Experts estimate that the two mutations carry distinct differences in virulence. If tests of imported cases start to show the European/US mutation, the risk of severe cases cannot be ruled out.

As of 29 Feb, Hong Kong had 95 patients with Wuhan pneumonia. The Department of Health Technology and Informatics at PolyU sequenced the virus from 50 of the patients. Of these, 44 locally infected cases included the "hotpot", "mahjong", "Hong Mei House" and "Fook Wai Temple" clusters which all carry the G251V mutation within the Orf3a gene. This genetic mutation never appeared in the Wuhan pneumonia's first gene map published in Mainland China in January.

The remaining 6 cases all had travel histories. Only patient #6, a 47-year old man who had worked as a cashier in Wuhan, tested positive for the G251V mutation. The virus genome in the remaining patients was similar to that of the first batch of patients in Wuhan. This included patient #66, a 75-year old man who travelled to Zhangmutou in Dongguan six times for meals with friends before the Lunar New Year. The study reported that the the virus in his wife, daughter and son-in-law had the same genes, inferring that he was the source of outbreak in his family.

The study found that in the "Fook Wai Temple" cluster's 13 cases leading up to the end of February, the virus in patient #102, a 43-year old male abbot who visited Mount Emei before the Lunar New Year, had a gene map most similar to the first one published in China (minimal mutation). The virus genome in other patients showed incremental changes, suggesting that the abbot was the initial culprit of "virus spreading". The research is currently undergoing peer review and will be published in academic journals upon completion.

One of the researchers, associate professor Dr Gilman Siu, pointed out that the virus’s RNA would occasionally mutate. "Unlike the flu virus, genetic drift or shuffling would be a big issue." However, none of Hong Kong cases carried the P314L mutation derived from the Orf1b gene common to Europe and the US. This may indicate higher virulence than G251V and could explain the higher mortality rates seen in those areas. He surmised that some Hong Kong patients with a travel history from March to April could also have the P314L mutation, which would not rule out the risk of higher illness severity compared to other patients. "In fact, the number of patients in critical condition is greater than that in February."

He added that there were more than a thousand cases in Hong Kong but genetic analysis was only available for the first 70 cases. He stated that our progress was slower than in other countries. It is estimated that it will take 6 to 9 months to complete the analysis of the first thousand cases.

Source: https://bit.ly/2yAdePw

*The original research paper relating to the Hong Kong cases can be found here: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3559611