Epidemiology of new influenza A (H1N1) virus infection, United Kingdom, April – June 2009

Following the previous report to Eurosurveillance on 14 May 2009, the number of confirmed cases of new influenza A(H1N1) has continued to increase in the United Kingdom. By 31 May, UK surveillance activities had detected a total of 252 confirmed cases. Seventy (28%) were related to travel to the United States and Mexico. There is evidence of spread in households, schools and the community with increases in secondary (n=40), tertiary (n=125) and sporadic (n=13) cases. The new influenza A(H1N1) virus infection continues to cause a mild illness predominately affecting younger age-groups with a low rate of hospitalisation.