On April 15 and 17, the Atlanta-based Centers for Disease Control and Prevention determined that nasal samples from two children in Southern California contained a swine flu virus that had never been seen.
It was found to contain bits of bird and human flu, and touched off fears of a global outbreak. As the disease spread, the World Health Organization declared it the first global flu pandemic in 40 years.
In the United States, some of the initial response plans for the new swine flu, an H1N1 strain, envisioned "people dropping dead in the streets," recalled Dr. Beth Bell, a CDC epidemiologist.
The scare over the swine flu has subsided, but health officials warn we are not out of danger.
"Our biggest concern is that the virus could change, mutate to become more deadly," Dr. Tom Frieden, director of the CDC, said last week.
As winter approaches, a major worry is a one-two punch in which a resurgent swine flu batters young people before the vaccine is widely available, while the ordinary flu strikes the elderly.
To date, swine flu has hospitalized hundreds of thousands of people worldwide and killed at least 4,500, including at least 600 in the United States.
Tylenol and babies' vaccines may not mix
Giving babies Tylenol to prevent fever when they get childhood vaccinations may backfire and make the shots a little less effective, new research suggests.
The CDC's is the first major study to tie reduced immunity to the use of fever-lowering medicines. Although the effect was small and the vast majority of kids still got enough protection from vaccines, the results make "a compelling case" against routinely giving Tylenol right after vaccination, say doctors from the CDC.
The study, published in today's issue of the British medical journal Lancet, only looked at preventive use of Tylenol — not whether it could be used after a fever develops. Many parents give Tylenol or its generic twin, acetaminophen, before or after a shot just to prevent fever. The CDC's vaccine advisory panel said it is a reasonable use for children at high risk of seizures, which can be triggered by fevers.