On Nextstrain, researchers build family trees of viral genetic sequences. It allows them to see if two cases of Covid-19 are closely related to one another. | Nextstrain

The US lags behind on yet another tool to end the pandemic: viral genetic sequencing.

There’s a reason why a new, more contagious variant of SARS-CoV-2 appeared first in the UK: The country does a lot of viral genetic sequencing. Since the start of the pandemic, researchers in the UK have uploaded 151,859 individual SARS-CoV-2 sequences to GISAID, an international platform for sharing viral genomic data. That’s the highest number of sequences shared by any country in the world.

If a more contagious strain of SARS-CoV-2 first evolved in the United States, scientists likely would not have noticed so quickly. Despite having a larger population than the UK, a sophisticated biomedical research