Washington, April 29 : The new Omicron subvariant XBB.1.16 is spreading fast in the US, becoming the second dominant Covid-19 strain in the country, according to the latest data by the Centers for Disease Control and Prevention (CDC). The subvariant, referred to as "arcturus", has accounted for about 12 per cent of new weekly Covid-19 cases reported in the country, up from 7.4 per cent the week prior, Xinhua news agency quoted the CDC data published on Friday as saying. Experts warned the percentage is expected to increase in the coming weeks, possibly become the next dominant coronavirus strain in the country. The highly transmissible Omicron subvariant XBB.1.5 remains the dominant strain in the US and accounted for about 68.8 per cent of new Covid-19 cases this week, the CDC data revealed. The World Health Organization is monitoring XBB.1.16, which is contributing to the ongoing resurgence of Covid-19 in India. The US continues to remain the worst hit country in the world with the highest number of Covid-19 cases and deaths. As of Saturday morning, the country's overall caseload and death toll stood at 106,627,427 and 1,159,824, respectively. /IANS