There are already small changes in the virus that have occurred independently of one another several times around the world, which suggests that the mutations are helpful for the pathogen. The mutation that affects antibody susceptibility – technically known as the 69-70 deletion, which means that letters are missing from the genetic code – has been seen at least three times: in Danish mink, in people in the UK, and in an immunocompromised patient who became much fewer sensitive to convalescent plasma.
“This thing transmits, it acquires, it keeps adapting,” said Dr. Ravindra Gupta, a virologist at the University of Cambridge, who last week detailed the recurring genesis and spread of the deletion. “But people don’t want to hear what we’re saying, namely: this virus is going to mutate.”
The new genetic deletion changes the spike protein on the surface of the coronavirus that it needs to infect human cells. Variants of the virus with this deletion appeared independently in Thailand and Germany in early 2020 and were distributed in Denmark and England in August.
Scientists initially thought the new coronavirus was stable and unlikely to escape a vaccine-induced immune response, said Dr. Deepti Gurdasani, a clinical epidemiologist at Queen Mary University in London.
“But in the last few months it has become very clear that mutations can occur,” she said. “As selection pressure increases with mass vaccination, these mutants will likely appear more frequently.”
Several recent publications have shown that the coronavirus can evolve to avoid detection by a single monoclonal antibody, a cocktail of two antibodies, or even a convalescent serum given to a particular individual.
Fortunately, the body’s entire immune system is a much more formidable enemy.
The Pfizer-BioNTech and Moderna vaccines induce an immune response only to the spike protein that the coronavirus carries on its surface. But every infected person produces a large, unique and complex repertoire of antibodies to this protein.