A ‘powerful force’
“We hope for the best, that vaccine resistance has not developed, but caution that evolution is a very powerful force, and maintaining some precautions during vaccination may help to control that evolution,” said Dr. Kondrashov.
The investigators are relying on epidemiologists to determine which measures are most effective.
“It’s necessary to vaccinate as many people as fast as possible and as globally as possible and to maintain some level of nonpharmaceutical intervention to ensure rare variants have a chance to be suppressed instead of spread,” concluded Dr. Kondrashov.
He’s pessimistic because many countries are still having difficulty accessing vaccines, and vaccine efficacy wanes slightly over time. The authors warned that “the emergence of a partially or fully vaccine-resistant strain and its eventual establishment appears inevitable.”
The worst-case scenario is familiar to population biologists: rounds of “vaccine development playing catch up in the evolutionary arms race against novel strains,” the authors wrote.
Limitations of the study are that some parameters of the rate of evolution for vaccine-resistant strains aren’t known, and in creating the model, consideration was not given to effects of increased testing, rigorous contact tracing, rates of viral genome sequencing, and travel restrictions.
Rather, the model illustrates general principals by which vaccine resistance can evolve, Dr. Kondrashov said.
A version of this article first appeared on Medscape.com.