SARS-CoV-2 variants as super cell fusers: cause or consequence of COVID-19 severity?

The most severe forms of coronavirus disease 2019 (COVID-19) are often associated with the presence of syncytia in the lungs resulting from cell-cell fusion mediated by the SARS-CoV-2 spike protein. In this issue, Rajah and colleagues show that the SARS-CoV-2 alpha, beta, and delta variants promote enhanced syncytia formation as compared to the original strain.