Why Is Coronavirus So Infectious? Researchers Say Mutation Is Much More Efficient At Infecting Cells

Researchers at Northwestern University’s medical school in Chicago say a mutation in the coronavirus has made it much more contagious – but doesn’t appear to make people any sicker.

Egon Ozer, an infection disease specialist at the Feinberg School of Medicine, found in examining samples of the coronavirus genetic structure a change in one of the amino acids created a spike protein on the virus’ surface, allowing it to more easily penetrate nearby cells, allowing it to replicate faster, creating more copies that can be passed on.

The mutation, which has become the dominate form of the virus worldwide, has been officially designated D614G and is present in about 70% of the 50,000 genomes uploaded to a shared scientific database.

“The epidemiological study and our data together really explain why the [G variant’s] spread in Europe and the U.S. was really fast,” Hyeryun Choe, a virologist at Scripps Research, told the Washington Post. Choe is the lead author on an unpublished study on the mutation.

In the early days of the outbreak in Wuhan, the original virus’ spike protein often broke, making it more difficult for it to enter cells. The mutated cells have more spike proteins and they’re less likely to break, she said.

Experiments at the New York Genome Center at New York University indicate the mutated virus is much more efficient at entering human cells.

“We were shocked,” NYU geneticist Neville Sanjana told the Post.

Until an effective vaccine is developed, the population remains at risk of infection, although it appears many people are asymptomatic. Last week, Dr. Robert Redfield, head of the Centers for Disease Control and Prevention, said the infection rate may be 10 times higher than testing indicates.

Worldwide, there have been more than 10 million confirmed cases of the virus and nearly 502,800 deaths. In the U.S., about 2.56 million infections have been confirmed and nearly 126,000 deaths.

In recent weeks, infections started to surge again in the U.S. and elsewhere as mitigation restrictions were loosened. The governors of Texas and Florida have ordered bars to close again because of spiking case counts.