The fast-spreading Omicron XBB.1.5 is estimated to make up nearly half of U.S. COVID-19 cases, data from the Centres for Disease Control and Prevention (CDC) showed on Friday, putting it on track to become the dominant subvariant in the United States.<br />''<br />''It is estimated to account for 49.1 per cent of COVID cases in the country a jump from 37.2 per cent last week. The subvariant is an offshoot of XBB, a combination of two other Omicron sub-variants, that has been rapidly gaining ground in the United States, particularly in the northeast.<br />''<br />''The World Health Organisation's Director-General, Tedros Adhanom Ghebreyesus, said earlier this month, Omicron XBB.1.5 has been on the rise globally and identified in over 25 countries.<br />