A single ‘escape mutant’ shouldn’t render a Covid-19 vaccine ...


A single ‘escape mutant’ shouldn’t render a Covid-19 vaccine useless

Despite the disappointing news about the Oxford/AstraZeneca vaccine, there still is some reason for hope

Sarah L Caddy

Several coronavirus variants that have emerged in recent weeks have scientists worried. The variants, which were first identified in the UK (B117), SA (B1351) and Brazil (P1 and P2), have several mutations in the spike protein (https://theconversation.com/new-coronavirus-variant-what-is-the-spike-protein-and-why-are-mutations-on-it-important-152463) — the little projections on the surface of the virus that help it latch on to human cells. This protein is the target for all Covid-19 vaccines now being rolled out. So will the vaccines protect us from these new variants?

Viruses are often not good at making identical copies of themselves. This means that each time they replicate, changes or “mutations” in their genetic sequence can occur. Most of these mutations are harmless and have no effect on the virus. However, a small minority may allow the virus to avoid being recognised by components of our immune system. Such mutations are known as “escape mutants”.

For months, scientists have predicted that mutations in the spike protein of SARS-CoV-2 could emerge, rendering antibodies ineffective. Until recently, this was mostly studied for drugs called monoclonal antibodies. These are artificial antibody treatments, such as REGN-COV2, developed by Regeneron. A spike protein monoclonal antibody only recognises a single part of the spike. This means a single mutation could, in theory, stop the antibody from binding and neutralising the virus...

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