The regular flu kills between 46 and 88 children a year, according to the Centers for Disease Control and Prevention. That suggests deaths from the new H1N1 virus could dramatically outpace children's deaths from seasonal flu, if swine flu continues to spread as it has.
CDC officials say 10 more states, a total of 37, now have widespread swine flu. A week ago, reports suggested that cases might be leveling off and even falling in some areas of the country, but that did not turn out to be an enduring national trend.
"We are seeing more illness, more hospitalizations, and more deaths," the CDC's Dr. Anne Schuchat said at a press conference Friday.
The new virus, first identified in April, is a global epidemic. The CDC doesn't have an exact count of all swine flu deaths and hospitalizations, but existing reports suggest more than 600 have died and more than 9,000 have been hospitalized. Health officials believe millions of Americans have caught the virus.
The virus is hitting young people harder. Experts believe older people are suffering from it less, perhaps because they have a bit of immunity from exposure over the years to somewhat similar viruses.
Most healthy children recover and often suffer only mild symptoms. But some have died from it, often from a second infection that moves in while the body is weakened from the flu.
Kids with asthma or chronic heart or respiratory conditions also are at greater risk for serious complications.
Experts say it's important for parents to watch their children's symptoms carefully. If a child appears to get better, but fever and a cough return, there may be a second infection. Other trouble signs are rapid or difficult breathing or bluish skin color.
Vaccinations against swine flu began this week and so far, states have ordered 3.7 million doses. Demand is exceeding supply, and people seeking the vaccination should ask their state or local health department where to go, said Schuchat, who heads the CDC's National Center for Immunization and Respiratory Diseases.
Health officials also said more data is trickling in from several clinical trials of the new vaccine, and so far no serious side effects have been reported.
Preliminary results from one study indicate that both a seasonal flu shot and a swine flu shot are effective when given during the same doctor's office visit. However, the government is not recommending that people get the nasal spray versions of the seasonal and swine flu vaccines at the same time.
The nasal sprays contain weakened, live virus, and the government doesn't have data on how a person's immune system would react to exposure to both at once, said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.