New Delhi, April 2 : The latest subvariant of Omicron XBB.1.16 is one to watch, even as it is fuelling a steady rise in cases in India, according to the World Health Organization (WHO). The WHO has added XBB.1.16 as the sixth variant under monitoring on March 22, the global health body said in its weekly update on the pandemic. It added that though global cases and deaths continue to decline, some countries -- including India -- are reporting recent spikes in cases. "XBB.1.16 has replaced other circulating sub-variants in India," Maria Van Kerkhove, the WHO's Covid-19 technical lead, said at a recent press briefing. "So this is one to watch. It's been in circulation for a few months," she said. So far, there are about 800 sequences on XBB.1.16 from 22 countries, mostly from India. Van Kerkhove added that XBB.1.16 has a similar profile to XBB.1.5, but has additional changes in the spike protein. In lab studies, XBB.1.16 has shown signs of increased infectivity as well as potentially increased pathogenicity, she noted. Van Kerkhove said "we haven't seen a change in severity in individuals or in populations," but "one of the things we are very concerned about is the potential for the virus to change to become not only more transmissible but more severe. "So we have to remain vigilant," she said. Meanwhile, India this week reported its highest levels Covid cases in six months. On Sunday, the country recorded a single-day jump of 3,824 Covid-19 infections, the biggest in 184 days. With the sudden spike, the number of active cases in the country increased to 18,389, according to Union Health Ministry data. Five new fatalities were also reported -- one each from Delhi, Haryana, Kerala and Rajasthan in a span of 24 hours and one was reconciled by Kerala. Globally, Iran, Kuwait, Libya, UAE and Qatar have reported the biggest proportional increases in Covid cases over the last 28 days. Indonesia has also reported a modest rise in cases. According to the US Centers for Disease Control and Prevention (CDC), XBB.1.5 has reached saturation, making up 87.9 per cent of samples. Three other Omicron subvariants XBB.1.9.1, XBB, and XBB.1.5.1 has shown positive growth, the agency reported in its biweekly data summary. /IANS