Optimized second-generation mRNA vaccine demonstrated protection against COVID-19

Nov. 23, 2021

In a head-to-head test of a revised version of an investigational mRNA vaccine, CV2CoV, compared with the original version, researchers at Beth Israel Deaconess Medical Center (BIDMC) assessed the vaccines’ ability to provoke an immune response as well as their protective efficacy against COVID-19 in non-human primates.

Their findings, published in Nature, show the modifications made to the second-generation CV2nCoV induced a ten-fold higher antibody response than the original version, CVnCoV. In a recent phase 2b/3 clinical trial, the original version of the mRNA vaccine against COVID-19 — known as CVnCoV and developed by CureVac — reported approximately 48 percent efficacy against symptomatic disease.

The researchers’ data revealed that, while CVnCoV provided only modest reduction in viral loads in immunized animals later challenged with SARS-CoV-2, CV2CoV induced ten-fold higher antibody responses and dramatically lowered viral loads. They also report that CV2CoV induced antigen-specific memory B cell responses and T cell responses. Moreover, CV2CoV raised similar antibody titers in macaques compared with the BNT162b2 vaccine developed by Pfizer.

“The improved characteristics of CV2CoV compared with CVnCoV may translate into increased efficacy in humans, and clinical trials of the second-generation vaccine are planned,” said Barouch, who is also a member of the Ragon Institute of MGH, MIT and Harvard.

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