Why the COVID-19 Delta Variant Spreads So Easily and Infects People So Quickly


Findings have implications for next-generation COVID-19 vaccines and treatments.

The Delta variant of SARS-CoV-2 has swept the globe, becoming the dominant variant within just a few months. A new study from Boston Children’s Hospital, published on October 26, 2021, in Science, explains why Delta is so easily spread and infects people so quickly, and suggests a more targeted strategy for developing future COVID-19 vaccines and treatments.

Last spring, study leader Bing Chen, PhD, showed how several earlier SARS-CoV-2 variants (alpha, beta, G614) became more infectious than the original virus. Each variant acquired a genetic change that stabilized the spike protein — the surface protein on which current vaccines are based. This mutation increased the variant’s ability to get into cells.

The Delta variant, which emerged soon after, is the most infectious variant known to date. Chen and colleague set out to understand why. “We thought there must something very different happening, because Delta stands out among all the variants,” Chen says. “We found a property that we think accounts for its transmissibility and so far appears to be unique to Delta.”



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