Beefed-up US sequencing efforts are turning up variants with new or rarely seen mutations that are harder to make sense of. Kamil teamed up with researchers in New Mexico because they had also observed rising numbers of cases caused by a variant, which they dubbed Pelican, bearing a mutation they hadn’t seen before. They identified several other variants in US sequencing data that carried a similar change. (All were given bird nicknames, including Robin, Yellowhammer and Mockingbird.)

The mutation, called Q677P, sits near a region of the spike protein that needs to snap in two to allow the viral particle to enter a host cell. Mutations in this region occur in fast-spreading variants such as B.1.1.7, but Kamil says the Pelican variant is, for now, one to watch rather than worry over. “It’s too early to say with any scientific confidence that it’s a particularly worrisome mutation,” he says.

Last week, researchers in California raised a red flag over variants found there that carry a spike protein mutation called L452R1. A team at the University of California, San Francisco (UCSF) found that a variant with the mutation was rising rapidly in one city neighbourhood, from being present in 16% of sequenced samples in November to more than half in mid-January. Another UCSF team found, in lab tests, that a variant with the L452R mutation was more infectious and less susceptible to antibodies, according to media reports.