Variants spread rapidly through populations and become the dominant strains, at least locally. There has been an enormous effort to understand the extent, function, and epidemiological consequences of these variants. In the past few months, genome sequencing efforts isolated many SARS-CoV-2 variants throughout the world.

Other variants were isolated in laboratories using monoclonal antibodies or pseudotyped viruses, which are virus particles whose envelope proteins can be dictated by researchers to measure antiviral compounds and antibody responses. Rino Rappuoli and his team of Italian researchers took this one step further.