Swine flu outbreak

Mexico City, Mexico: Women wearing surgical masks pray at the deserted Zocalo plaza Photograph: Dario Lopez-Mills/AP

Mexico City: Police officers wearing surgical masks at the entrance of the metropolitan cathedral Photograph: Dario Lopez-Mills/AP

Mexico City: The empty Basilica of Our Lady of Guadalupe during mass following the deadly swine flu outbreak. More than 500 cultural and athletic events have been cancelled by government order in the capital city alone Photograph: Luis Acosta/AFP/Getty Images

Mexico City: A mariachi wears a mask as he plays the violin Photograph: Jorge Dan/Reuters

Mexico City: A woman gets her throat checked by medical personnel before entering a bar Photograph: Jorge Dan/Reuters

Mexico City: A soldier hands out surgical masks in the Zocalo plaza Photograph: Gregory Bull/AP

Mexico City: A tourist receives a ritual cleansing from a shaman Photograph: Mario Guzman/EPA

Mexico City: A street vendor takes advantage of the outbreak by selling face masks Photograph: Mario Guzman/EPA

Tokyo: A girl's face is shown in red on a thermographic camera during a check upon her arrival on a flight from Mexico City at Narita international airport Photograph: Yuriko Nakao/Reuters

Tijuana, Mexico: Pharmacy workers advise customers while wearing surgical masks Photograph: Sandy Huffaker/Getty Images

Seoul, South Korea: Travellers arriving at Incheon airport undergo stricter quarantine inspections Photograph: Yonhap/EPA

Chuncheon, South Korea: A South Korean disinfection truck sprays disinfectant against a possible swine flu outbreak at a pork farm Photograph: Lee Sang-hack/AP

Denpasar, Bali, Indonesia: A health official monitors arriving passengers with thermal scanners at Ngurah Rai international airport. Indonesia increased surveillance at all entry points for travelers with flu-like symptoms using devices at airports that were put in place years ago to monitor for Sars and bird flu Photograph: Dita Alangkara/AP

Chuncheon, South Korea: A health official in a protective suit sprays disinfectant against a possible swine flu outbreak at a pork farm Photograph: Lee Sang-hack/AP

Hong Kong, China: Health workers watch a bank of monitors which display information on the temperatures of incoming passengers at the international airport in Hong Kong - a city at the forefront of the Sars epidemic in 2003 Photograph: Vincent Yu/AFP/Getty Images

Narita, Tokyo: A quarantine official is reflected on a monitor as he checks the temperatures of arriving passengers on a thermographic imaging device placed at Narita international airport Photograph: Yuriko Nakao/Reuters

Anyang, South Korea: Quarantine researchers check samples of Mexican pork meat at the National Veterinary Research and Quarantine Service Photograph: STR/AFP/Getty Images

Singapore: A health screening official checks a passenger for his temperature arriving at terminal three of Changi airport. In light of the outbreak of swine flu cases in Mexico and the US, all passengers arriving at Singapore's main Changi airport are being screened for flu symptoms Photograph: How Hwee Young/EPA

The antiviral drug Tamiflu. The British government is preparing for a possible swine flu outbreak in the UK Photograph: Sang Tan/AP

Almansa, Spain: A guard gestures to journalists outside the Hospital General in Almansa, where the only confirmed case of swine flu in Spain is hospitalised. Spain's Health Ministry confirmed Europe's first case of swine flu and said another 20 people are suspected of having the disease. Health Minister Trinidad Jiménez said the patient is a young man who had recently returned from Mexico where he had been as part of his university studies Photograph: Alberto Saiz/AP

Helsinki, Finland: A nurse wearing protective clothing puts on a head-covering at the infectious diseases ward in Aurora Hospital Photograph: Jarno Mela/AFP/Getty Images

Madrid, Spain: A passenger wearing a mask arrives at Barajas Airport Photograph: Arturo Rodriguez/AP

Luxembourg: The European commissioner for health, Androulla Vassiliou, speaks with the media as she arrives for a meeting of EU foreign ministers at the Kiem centre on Monday 27 April Photograph: Virginia Mayo/AP

Washington DC, US: Barack Obama addresses the National Academy of Sciences. The president said he was closely watching an outbreak of swine flu in the United States, where 20 cases have so far been identified, but urged people to remain calm, saying: 'This is obviously a cause for concern and requires a heightened state of alert, but it's not a cause for alarm' Photograph: Dennis Brack /EPA

New York, US: A man wearing a protective mask stands on a subway in Grand Central Station Photograph: Justin Lane/EPA