Like all living things, viruses evolve in response to selection pressures. The immune response of the host is one of the selection pressures that drive viral evolution. Accordingly, one outcome of viral evolution can be to “escape” the immune response of its host.
The authors point out that most “successful vaccines have had a commonality in that they generally target infectious pathogens with a low rate of mutation.” SARS-Cov-2, however, has a relatively high rate of mutation, meaning that it evolves quickly.
The authors are concerned that the Covid vaccines currently available may be driving viral evolution toward “escape” in ways we don’t fully understand. They note that natural immunity through infection is far more robust than the immunity current vaccinations confer because the natural antibodies target more components of the virus. Theoretically, it should be harder for the virus to escape the natural immune response than the artificial one. By the same token, we cannot predict what a viral escape from the artificial immunity might produce.
Thus, the authors claim “[T]here is an urgent need for debate on the issue of vaccinating people who have already recovered from Covid-19.”