In Hong Kong, two persons have died after contracting the H1N1 virus. Hong Kong's Hospital Authority said that a total of 35 people were being treated for H1N1 in intensive care units in the city, with four critical cases confirmed in the last two days. According to the World Health Organisation, H1N1 has killed more than 18,400 people and affected practically all parts of the world since it was uncovered in Mexico and the United States in April 2009.