The UN health agency World Health Organisation (WHO) yesterday declared an international emergency over the deadly coronavirus from China -- a rarely used designation that could lead to improved international co-ordination in tackling the disease. "Our greatest concern is the potential for the virus to spread to countries with weaker health systems.... This is not a vote of no confidence in China," World Health Organization (WHO) chief WHO chief Tedros Adhanom Ghebreyesus told a briefing in Geneva.