Covid vaccine updates “will always be a step or two behind the evolution of the virus”. But scientists are hard at work developing technologies that make them “broadly protective,” i.e. capable of targeting future variants and related coronaviruses. An article published online in Nature.it anticipates the new generation of vaccines, from “mosaic” to “self-amplifying” ones.
Covid vaccines have saved more than 20 million lives. More than 50 have already been approved, and there are hundreds in early and late-stage clinical trials, with hundreds more being abandoned during development. Since viral variants can evade part of the immunity provided by the original vaccines, scientists are working on “next generation” vaccines: not only nasal and bivalent or updated ones, but also others based on new technologies and platforms.
The goal of some of these vaccines is to generate an immune response against particular regions of the spike protein that are conserved in the variants and one of these regions is the receptor binding domain (RBD). At least two teams, at the University of Washington in Seattle and at the California Institute of Technology (Caltech) in Pasadena, are developing “mosaic” vaccines, composed of a nanostructure to which spike protein fragments from 8 different coronaviruses are attached, which could protect against a variety of Sars-Cov-2-like viruses, including variants: in this case, when a B cell recognizes more than one RBD – by attaching itself to regions conserved by multiple virus species – it binds strongly, allowing the B cell to produce more antibodies. Studies, currently on animals, suggest positive results.
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