Already, there are small changes in the virus that have arisen independently multiple times across the world, suggesting the mutations are helpful to the pathogen. The mutation affecting antibody susceptibility — technically called the 69-70 deletion, meaning there are missing letters in the genetic code — has been seen at least three times: in Danish minks, in people in Britain, and in an immune-suppressed patient who became much less sensitive to convalescent plasma.
“This thing’s transmitting, it’s acquiring, it’s adapting all the time,” said Dr. Ravindra Gupta, a virologist at the University of Cambridge, who last week detailed the deletion’s recurrent emergence and spread. “But people don’t want to hear what we say, which is: This virus will mutate.”
The new genetic deletion changes the spike protein on the surface of the coronavirus, which it needs to infect human cells. Variants of the virus with this deletion arose independently in Thailand and Germany in early 2020, and became prevalent in Denmark and England in August.
Scientists initially thought the new coronavirus was stable and unlikely to escape vaccine-induced immune response, said Dr. Deepti Gurdasani, a clinical epidemiologist at Queen Mary University of London.
“But it’s become very clear over the last several months that mutations can occur,” she said. “As selection pressure increases with mass vaccination, I think these mutants will become more common.”
Several recent papers have shown that the coronavirus can evolve to avoid recognition by a single monoclonal antibody, a cocktail of two antibodies or even convalescent serum given to a specific individual.
Fortunately, the body’s entire immune system is a much more formidable adversary.
The Pfizer-BioNTech and Moderna vaccines induce an immune response only to the spike protein carried by the coronavirus on its surface. But each infected person produces a large, unique and complex repertoire of antibodies to this protein.