At a time when flu season should be ending or over, the CDC's flu season indicators are going up instead of down. As of May 9, 22 states had widespread or regional flu. The CDC's most recent data, for the week ending May 9, shows that about half of Americans with confirmed flu had the H1N1 swine flu. One of the most alarming signs of a flu pandemic is a lot of severe illness in people who don't usually suffer severe flu cases -- older children and young adults. Most of the 173 people hospitalized in the U.S. with H1N1 swine flu have been between 5-24 years old.
H1N1 swine flu has killed 1/114 patients with confirmed infection worldwide (and 1/1,200 in the U.S.). This is a much higher mortality rate than seasonal influenza. If Dr. Jernigan’s estimate is correct and there have been 4 deaths among 50,000 infections, the mortality rate of 1/12,500 is more similar to seasonal influenza. However, this assumes that all deaths due to H1N1 have been reported – also unlikely, so the mortality rate may be higher or lower.
Seasonal influenza kills between 1/1,000 (in age > 65) and 1/200,000 (age < 50). About 90% of deaths due to seasonal influenza occur in individuals age 65 or older. This does not appear to be the case for H1N1 swine flu.
We continue to recommend isolation and influenza testing for anyone who develops a febrile illness; prompt treatment with Tamiflu for those who test positive is appropriate. We do not recommend limiting Tamiflu treatment of flu-test positive patients to only those with other illnesses given the severity of illness seen with H1N1 in young, otherwise healthy individuals.
Standard precautions (hand washing, etc.) should also be continued.
Comments / Posted by Scott W. Yates, MD, MBA, MS, FACP
