The World Health Organization (WHO)  urged countries to recommend all those travelling to wear masks in view of the rapid spread of the new Omicron sub-variant XBB.1.5 across the world. <br />''<br />''WHO's senior emergency officer for Europe, Catherine Smallwood said, Passengers should be advised to wear masks in high-risk settings such as long-haul flights.<br />''<br />''latest highly transmissible Omicron variant XBB.1.5 has accounted for 27.6 percent of the Covid-19 in the United States so far till Sunday. The WHO officials said, subvariant has been detected in Europe as well in small but growing numbers.<br />''<br />''<br />