As we enter the second year of living with the new coronavirus SARS-CoV-2, the virus is celebrating its invasion of the world’s population with yet more mutated forms that help it to spread more easily from person to person.
In December, one, first detected in the U.K., has already raised alarms about whether the COVID-19 virus is now escaping from the protection that vaccines just being rolled out now might provide. The variant has also been found in the U.S. Already, U.K. officials have tightened lockdowns in England, Scotland and Wales. Over the holidays, more than 40 countries banned travelers from the region to keep the new strain from spreading to other parts of the world. Health officials are also concerned about different stress found in South Africa that could become more resistant to vaccine protection. This variant includes a few mutations in critical areas that antibodies generated by the vaccine target.
Exactly how the new strains affect infected people—such as whether they develop more severe symptoms—and whether they can lead to more hospitalizations and deaths, aren’t clear yet. But scientists are ramping up efforts to genetically sequence more samples from infected patients to learn how widespread they are. So far, there are enough hints to worry public health experts.
Just a few months after SARS-CoV-2 was identified in China last January, for example, a new variant, called D614G, superseded the original strain. This new version became the dominant one that infected much of Europe, North America, and South America. Virus experts are still uncertain over how important D614G, named for where the mutation is located on the viral genome, has been when it comes to human disease. But so far, blood samples from people infected with the strain show that the immune system can still neutralize the virus. That means that the current vaccines being rolled out worldwide can also protect against this strain since the shots were designed to generate similar immune responses in the body. “If the public is concerned about whether vaccine immunity can cover this variant, the answer is going to be yes,” says Ralph Baric, professor of epidemiology, microbiology, and immunology at the University of North Carolina Chapel Hill, who has studied coronaviruses for several decades.
The so-called N501Y variant (some health officials are also calling it B.1.1.7.), which was recently detected in the U.K. and the U.S., maybe a different story. Based on lab and animal studies, researchers believe this strain can spread more easily between people. That’s not a surprise, says Baric, since, to this point, most of the world’s population has not been exposed to SARS-CoV-2. That means that for now, the strains that are better at hopping from one person to another will have the advantage in spreading their genetic code. But as more people get vaccinated and protected against the virus, that may change. “Selection conditions for virus evolution right now favor rapid transmission,” he says. “But as more and more of the human population become immune, the selection pressures change. And we don’t know which direction the virus will go.”
The biggest concern right now, says Baric, is that there are already two or three variants of SARS-CoV-2 that have mutations in just such places, “where additional mutations can make a more significant change in terms of transmissibility or virulence.”