In a new study, researchers found that similar to bacteria evolving resistance to antibiotics, viruses can evolve resistance to vaccines, and the evolution of the COVID-19 virus could undermine the effectiveness of vaccines that are currently under development.
They also offered recommendations to vaccine developers for minimizing the likelihood of this outcome.
The research was conducted by a team from Pennsylvania State University.
A COVID-19 vaccine is urgently needed to save lives and help society return to its pre-pandemic normal.
As scientists have seen with other diseases, such as pneumonia, the evolution of resistance can quickly render vaccines ineffective.
The researchers specifically suggest that the standard blood and nasal-swab samples taken during clinical trials to quantify individuals’ responses to vaccination may also be used to assess the likelihood that the vaccines being tested will drive resistance evolution.
For example, the team proposes that blood samples can be used to assess the redundancy of immune protection generated by candidate vaccines by measuring the types and amounts of antibodies and T-cells that are present.
Much like how combination antibiotic therapy delays the evolution of antibiotic resistance, vaccines that are designed to induce a redundant immune response—or one in which the immune system is encouraged to target multiple sites, called epitopes—on the virus’s surface, can delay the evolution of vaccine resistance.
That’s because the virus would have to acquire several mutations, as opposed to just one, in order to survive the host immune system’s attack.
The researchers also recommend that nasal swabs typically collected during clinical trials may be used to determine the viral titer, or amount of virus present, which can be considered a proxy for transmission potential.
They noted that strongly suppressing virus transmission through vaccinated hosts is key to slowing the evolution of resistance since it minimizes opportunities for mutations to arise and reduces opportunities for natural selection to act on those mutations that do arise.
In addition, the team suggests that the genetic data acquired through nasal swabs can be used to examine whether vaccine-driven selection has occurred.
For example, differences in alleles, or forms of genes that arise from mutations, between the viral genomes collected from vaccinated versus unvaccinated individuals would indicate that selection has taken place.
One author of the study is David Kennedy, an assistant professor of biology.
The study is published in PLOS Biology.
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