Omicron variant now accounts for 95% of new Covid cases in US: CDC

The omicron variant accounted for 95% of new coronavirus infections last week, according to US health officials' latest estimates.

The Centres for Disease Control and Prevention posted its newest estimates Tuesday. The CDC uses genomic surveillance data to make projections about which versions of the COVID-19 viruses are causing the most new infections.

The latest estimates suggest a dramatic swing - in just one month - in which version of the coronavirus is most abundant. Beginning in late June, the delta variant was the main version causing US infections. The CDC said more than 99.5% of coronaviruses were delta as recently as the end of November.

The CDC's estimates are based on coronavirus specimens collected each week through university and commercial laboratories and state and local health departments. Scientists analyse their genetic sequences to determine which versions of the COVID-19 viruses are most abundant.

However, those specimens represent just a small fraction of what's out there. More than 2.2 million cases were reported in the last week in the US. The CDC has been revising estimates for past weeks as it gets more data.