“I would expect a similar trajectory” in the United States, said Trevor Bedford, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle. The variant probably accounts for less than 1% of cases now, he estimated, but it may constitute most cases by March.
The variant has 23 mutations, compared to the original virus discovered in Wuhan, China. Seventeen mutations have appeared since the virus diverged from its most recent ancestor, said Muge Cevik, an infectious disease specialist at the University of St. Andrews in Scotland and a scientific adviser to the British government.
The speed with which the virus has acquired so many changes worries scientists, who expected the coronavirus to evolve much more slowly.
Current vaccine candidates are expected to continue to protect people from disease, several experts said. But the appearance of the new variant, which contains at least one mutation that weakens the body’s immune protection, makes it likely that vaccines may need regular adjustments as much as to remain effective against the flu virus.
Scientists are still unsure how the mutant spreads more easily. Initial estimates were about 70% higher transmissibility, but the number has been revised to 56% and could fall further, said Cevik.
But with every new person he infects, the coronavirus is also more likely to mutate and therefore more likely to occur in mutations that give him an advantage – making him more transmissible, for example, or less susceptible to the immune system.
“If you have enough of this happening, huge amounts of virus replication around the world, then you will get many different variants,” said Dr. Dan Barouch, virologist at Beth Israel Deaconess Medical Center in Boston.