TORONTO -- Scientists are cautioning that it鈥檚 still too early to know how the novel coronavirus (SARS-CoV-2) mutates, after a preliminary study in the U.S. claimed that a new strain of the virus has emerged that is more dominant and contagious than the original.
The preprint study by scientists at Los Alamos National Laboratory in New Mexico was , a website for academics to share their research before it鈥檚 peer-reviewed.
In the paper, the scientists said they discovered a new strain of the coronavirus, which first appeared in Europe in February. Since then, the new strain migrated to the U.S. East Coast and other regions and has become the dominant form of the virus in the world, according to the researchers.
The study鈥檚 authors said this one particular mutation, named D614G, appears to be more contagious than its predecessors because it has quickly infected more people than earlier strains of the virus that first emerged in Wuhan, China.
The scientists came to this conclusion by analyzing more than 6,000 coronavirus sequences from around the world, which were collected by the German-based organization the Global Initiative for Sharing All Influenza Data (GISAID).
They tracked the virus across different regions since its emergence and said they identified 14 mutations related to the now-infamous spike protein that is visible on the surface of the virus. They focused their attention on the spike protein because this is what allows the virus to enter human respiratory cells.
Of the mutations they discovered, the researchers said D614G appeared to be of the most concern because it became dominant wherever it was spread, although they said it鈥檚 still unclear why that is.
What鈥檚 more, the study didn鈥檛 show that the mutated strain of the virus actually made people sicker. The team studied data from 453 hospitalized patients in Sheffield, England and found that, while people with the particular mutation had higher viral loads in their samples, they weren鈥檛 sicker or in the hospital for longer periods.
鈥淭here was, however, no significant correlation found between D614G status and hospitalization status,鈥 the study said.
While the academics didn鈥檛 suggest the mutated strain was more lethal than its predecessors, they did warn of a possible risk that coronavirus patients will be 鈥渟usceptible to a second infection鈥 if they believe they have immunity to the virus after being infected with only one strain of it.
The scientists said the newly discovered strain was of 鈥渦rgent concern鈥 as it could have important implications for vaccine development already underway if those scientists are not aware of its mutated form.
鈥榃E NEED MORE INFORMATION鈥
While the suggestion of a more virulent mutated strain of coronavirus might stoke fears, experts in the field say more evidence is needed to prove its existence.
Rob Kozak, a clinical microbiologist at Sunnybrook Hospital who helped isolate SARS-CoV-2 in March, said the fact that the virus is mutating is not a cause for alarm because all viruses mutate as part of their life cycles. He explained that when a virus makes contact with a host, it will make new copies of itself so it can go on to infect other cells.
鈥淎s the virus replicates, it makes mistakes in copying itself and some of these mistakes will accumulate over time,鈥 he told CTVNews.ca during a telephone interview on Thursday. 鈥淚t will replace one nucleic acid with another just by accident, so that the genome of the virus at the beginning of a flu season, for example, is going to be a little bit different from the one at the end.鈥
For the most part, mutations tend to be neutral and will have only a slight effect on how the virus functions. In some cases, mutations may actually weaken a virus and cause it to peter out.
On rare occasions, a mutation can benefit the virus and help it to proliferate, as the study suggests is happening with COVID-19.
Dr. Isaac Bogoch, an infectious diseases physician and scientist with the Toronto General Hospital, said the study didn鈥檛 prove that the mutated strain is more virulent just because it was more common in their sample size.
鈥淚t鈥檚 not to say it can鈥檛 happen. It鈥檚 not to say it won鈥檛 happen, but they don鈥檛 provide the level of proof to determine that this has happened,鈥 he said.
鈥淚t鈥檚 not that a mutation didn't occur. It鈥檚 not that there aren鈥檛 different variants of this virus around. But does this mutation confer some special advantage over other strains of this virus? And the answer is maybe, maybe not, but they don鈥檛 show that in this paper.鈥
Kozak said the researchers can鈥檛 prove that the mutation is associated with better transmission or more virulence until they start doing rigorous scientific experiments using animals and cell cultures.
鈥淢utations on their own don鈥檛 really mean anything until we actually do proper animal models and proper scientific experiments to understand it,鈥 he said.
Kozak also said the study鈥檚 sample size of genomes comprised of only about one per cent of all the viruses out there from coronavirus, which has infected more than 3.8 million people globally.
鈥淲e鈥檙e not really getting a very fulsome picture of everything that鈥檚 there,鈥 he said.
The microbiologist said the study also didn鈥檛 take into account epidemiological factors, such as how those with the virus isolated themselves or if they travelled extensively while they were infected.
鈥淚f a country really locked down, put in social distancing, insisted that businesses be shut down, you鈥檇 probably see there might be less transmission of a particular virus based on that,鈥 he explained.
As for the study鈥檚 potential impact on vaccine development, the team from Los Alamos National Laboratory explained that was why they published the results of their research before it had been peer-reviewed.
鈥淭hese findings have important implications for SARS-CoV-2 transmission, pathogenesis and immune interventions,鈥 the authors wrote.
Bette Korber, a computational biologist and the study鈥檚 lead author, did not respond to a CTVNews.ca request for comment.
While Kozak agreed that sharing data is a good idea because it stimulates discussion and new ideas within the scientific community, he said it鈥檚 important to remember some of the study鈥檚 limitations and that it hasn鈥檛 undergone that proper peer-review process.
鈥淚t鈥檚 always a balance because you want to put information out there because maybe it鈥檒l be helpful to people,鈥 he said. 鈥淏ut it鈥檚 a risk when people don鈥檛 say 鈥榃e got to take this with a grain of salt. We need to not jump to conclusions. We need more information before we can really make a conclusion.鈥
