BEIJING, Oct. 13 — A/H1N1 influenza critical illness affects mostly the adolescents and relatively healthy adults, according to a Canadian and Mexican study as quoted by news reports Tuesday.

The study, published online on the Journal of the American Medical Association, was conducted during the first phase of infection between March 18 and June 1 in Mexico and April 16 through August 12 in Canada.

The study showed that out of 899 people admitted to six Mexican hospitals with confirmed or probable A/H1N1 infections during the period studied, the median age of the 58 critically ill patients was 44 years old.

The Canadian A/H1N1 patients’ average age in the studied period was 32.3 years old, with 50 people (29.8 percent) under the age of 18, according to the study.

The study concluded that the A/H1N1 influenza caused serious illness predominantly in young patients with few major underlying diseases.

At least 4,525 people have died from A/H1N1 infections since April and there have been at least 378,223 laboratory-confirmed cases, the World Health Organization said Friday. 

On Xinhua Web site: http://news.xinhuanet.com/english/2009-10/13/content_12222710.htm