How a mutant coronavirus strain dominated the world: Scientists discover change to COVID-19 variant that lets it copy itself more efficiently – making it more infectious (but not more deadly)

• Researchers found the most dominant strain of the virus was a mutation of the original variant called G614
• The G strain is not a deadlier version, but it allows the virus to copy itself more easily and create higher viral loads in patients
• Antibodies from recovered patients neutralized the G virus just as well as, if not better then, the original virus 

A small change to a variant of the novel coronavirus has helped it better copy itself but not make it more deadly, a new study suggests.

Researchers found there were two strains of the virus circulating when it reached the US: the original D614 and a mutation, G614. 

This mutation is not a deadlier version of the coronavirus but it does help the virus copy itself better, which results in a higher viral load in patients. 

Researchers found the most dominant strain of the virus by mid-March was a mutation of the original variant called G614 (right, in blue), not the original virus D614 (left, in green)

The G strain is not a deadlier version, but it allows the virus to copy itself more easily and create higher viral loads in patients. Pictured: Paula Johnson, a nurse, administers a deep suction tube into the lungs of a coronavirus patient, in the ICU of Roseland Community Hospital in Chicago, Illinois, April 22

Dr Erica Ollmann Saphire, a professor of at the La Jolla Institute of Immunology in California, says viruses often mutate to ‘escape’ antibodies created by our immune systems.

This phenomenon of viruses making enough changes to ‘drift’ away from the original virus is known as antigenic drift.

It’s one reason why new flu shots are needed every fall, because the dominant strain is often so different from the one the year before.  

Health experts say coronavirus mutates at a slower rate than several other respiratory viruses, particularly the the flu.

For the study, published in the journal Cell, the team tracked the spread of both the G and D viruses. 

They found that while both the D virus and the G virus spread widely around the world, the G strain was more dominant by mid-March. 

Next, researchers analyzed at antibody samples from six San Diego residents who had previously been infected with COVID-19.

They wanted to see if which variant would be harder to neutralize.

Results showed the new G virus was just as well neutralized – and sometimes even better – as the original D virus. 

This means the immune system doesn’t need to produce more or better-acting antibodies against the G virus, despite it being better at spreading. 

‘These findings suggest that the newer form of the virus may be even more readily transmitted than the original form,’ said senior author Dr Bette Korber, a fellow at Los Alamos National Laboratory.     

‘Whether or not that conclusion is ultimately confirmed, it highlights the value of what were already good ideas: to wear masks and to maintain social distancing.’ 

Saphire says the virus ‘wants’ to be transmissible, which is why many get a mild cases, or have no symptoms at all.

‘A virus that kills its host rapidly doesn’t go as far–think of cases of Ebola,’ she said.

‘A virus that lets its host go about their business will disseminate better – like with the common cold.’ 

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