Previous studies have estimated that B.1.1.7, which is now spreading rapidly in a number of countries, is roughly 50% more contagious than earlier coronavirus variants are. Yonatan Grad at the Harvard T.H. Chan School of Public Health in Boston, Massachusetts, and his colleagues examined the results of daily SARS-CoV-2 tests on 65 people infected with SARS-CoV-2, including 7 infected with B.1.1.7. The team looked at how long the virus persisted, and the amount of virus present at each time point.

In people infected with B.1.1.7, infections lasted an average of 13.3 days, compared with 8.2 days in people with other variants. There was little difference in the peak concentrations of the virus between the two groups.

These findings hint that B.1.1.7 is more easily transmitted than other variants are because people who catch it are infected for a relatively long time, and can therefore infect a larger number of contacts. This suggests that longer quarantine periods might be warranted for individuals infected with this variant.

The findings have not yet been peer reviewed.