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.