SARS-CoV-2 Could Evolve Resistance, Rendering COVID-19 Vaccines Ineffective – Health News Today

The series of illustrations on this page are a schematic illustrating three ways that standard samples from COVID-19 clinical trials can be repurposed to assess the risk that vaccine resistance will evolve. 1. The complexity of B-cell and T-cell responses can be measured using blood samples. Different neutralizing antibodies are depicted above in different colors. More complex responses indicate more evolutionarily robust immunity. Credit: Kennedy et al, 2020 (PLOS Biology, CC BY 4.0)

Similar to bacteria evolving resistance to antibiotics, viruses can evolve resistance to vaccines, and the evolution of SARS-CoV-2 could undermine the effectiveness of vaccines that are currently under development, according to a paper published today (November 9, 2020) in the open-access journal PLOS Biology by David Kennedy and Andrew Read from Pennsylvania State University, USA. The authors also offer recommendations to vaccine developers for minimizing the likelihood of this outcome.

“A COVID-19 vaccine is urgently needed to save lives and help society return to its pre-pandemic normal,” said David Kennedy, assistant professor of biology. “As we have seen with other diseases, such as pneumonia, the evolution of resistance can quickly render vaccines ineffective. By learning from these previous challenges and by implementing this knowledge during vaccine design, we may be able to maximize the long-term impact of COVID-19 vaccines.”

Collecting Viral Titer Data

2. The effect of vaccination on transmission potential can be assessed by collecting viral titer data using routine nasal swabs. Plaque assays from multiple vaccinated and control individuals are compiled into a histogram. Undetectable viral titers suggest little or no transmission potential, due to either complete immune protection or the absence of exposure. High viral titers suggest high transmission potential due to the absence of a protective immune response. Intermediate viral titers, marked above with an asterisk, suggest moderate transmission potential due to partial vaccine protection. Intermediate titers indicate an increased risk for resistance evolution since pathogen diversity can be generated within hosts and selection can act during transmission between hosts. Credit: Kennedy et al, 2020 (PLOS Biology, CC BY 4.0)

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…

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