Most of the 43 Covid-19 cases caused by the Omicron variant identified in the United States so far were in people who were fully vaccinated, and a third of them had received a booster dose, according to a US report published on Friday.

The US Centres for Disease Control and Prevention (CDC) said that of the 43 cases attributed to the Omicron variant, 34 people had been fully vaccinated. Fourteen of them had also received a booster, although five of those cases occurred less than 14 days after the additional shot before full protection kicked in.

While the numbers are very small...