Officials have been telling us for months that the H1N1 virus is, unlike seasonal flu, more likely to hit young people than older. Now a recent report from the Centers for Disease Control and Prevention says 36 children 18 or younger were among the 477 swine flu deaths reported between April and Aug. 8. That's about 1 out of every 13 deaths.

However, the CDC said there were complicating factors in most of those child deaths.

"In two-thirds of those, the child had at least one severe underlying illness or underlying disability -- cerebral palsy, muscular dystrophy, long-standing respiratory or cardiac problems," CDC Director Thomas Frieden said during a news teleconference last week.

"There were some children who didn't have an underlying condition and who did become severely ill, and they were generally infected also by bacteria, Dr. Frieden said. "When you get the flu, your immune system can be a little weakened. ... That's an important message for doctors to know that if someone has the flu, they get better, then they get worse again with high fever, that's a clue that maybe they should be treated with antibiotics."

But most children -- and most adults -- who get H1N1 have mild symptoms and recover quickly without treatment, Dr. Frieden said.

"The good news is that so far, everything that we've seen, both in this country and abroad, shows that the virus has not changed to become more deadly. That means that although it may affect lots of people, most people will not be severely ill."

Here are questions matched with advice from Dr. Frieden:

Q. Schools and colleges and universities across the country are reporting H1N1 outbreaks. Should I keep my child home if the virus hits his school or campus?

A. Not unless he is sick, in which case he will recover faster and also help contain the spread of the influenza if he stays home, Dr. Frieden said.

Q. Should the schools shut down during outbreaks?

A. Carnegie Mellon University weathered a sizable outbreak without closing down, and that's the kind of response the CDC is recommending.

"We hope that schools will continue," Dr. Frieden said. "Kids need to learn. Parents need to work. There's a lot that happens at schools that is very important."

Q. We've been told to avoid going to doctors' offices or emergency rooms unless absolutely necessary. When would it be absolutely necessary?

A. "For most people with the flu, there's no reason to see a doctor or go to the emergency department unless you're severely ill," Dr. Frieden said. "For example, you have trouble breathing or you have an underlying condition, such as diabetes, pregnancy, heart disease, lung disease.

"For people who do have an underlying condition, it's important to be seen promptly if you get a fever. That could make the difference between being severely ill and recovering well. Treatment in the first 48 hours can make a big difference in hastening your recovery."

Q. Vaccinations scare me. You always hear about negative after-effects.

A. "We are also looking very closely at the possibility of reports of adverse conditions," Dr. Frieden said. "We know that every year, there are cases of paralysis, Guillain-Barre syndrome, there are women who have miscarriages, there are people who have sudden death.

"In all those situations, we need to know very clearly how many we would expect if the vaccine doesn't cause any problems whatsoever. In an average flu season, just as an example, around 500,000 pregnant women get vaccinated. That's important because pregnant women are more likely to get severely ill from flu. So, it's a way of protecting them and ensuring that they have a healthy pregnancy.

"Among those 500,000 women, if they hadn't gotten vaccinated, we would have expected more than 1,000 miscarriages within a week after vaccine. If they're vaccinated, we expect about 1,000, 1,500 among women who were vaccinated.

"That's the kind of number we need to track and understand to see whether when we do see adverse event reports ... [whether] they're occurring at a higher rate than expected or not."

Q. Even if there are no "adverse numbers," I'm afraid to vaccinate my children. What is Dr. Frieden going to do?

A. "My kids will get the flu vaccine when it becomes available, and I would recommend that all school children get vaccinated," he said.

"We also are recommending that all people with underlying conditions get vaccinated, people who have asthma, diabetes, lung disease, heart disease, neuromuscular conditions, neurological conditions that increase their risk factors, and women who are pregnant."

Q. How much will getting an H1N1 vaccine cost?

A. It depends on where you get it.

"The vaccine itself will be free," Dr. Frieden said. "The administration [of the inoculation] may be charged by individual providers, although in the public health system, all vaccination will be free, we anticipate."

Q. The CDC has said two doses of vaccine probably will be necessary for a person to achieve H1N1 immunity, but China and the Swiss drug company Novartis, which is doing a trial in Britain, have said they have developed vaccines that would work after one dose. Why can't we?

A. "We look forward to seeing the data from China and elsewhere about vaccine efficacy. It's very important, and as soon as we see it, it will help us inform the policies here," Dr. Frieden said.

"I believe the Novartis study was done with a vaccine that has another material [or an adjuvant] added to it to boost the immune response. We don't anticipate that we will use adjuvanted vaccines in most of the scenarios that we anticipate now, although that could change, and we would expect that the likelihood of needing two doses with a vaccine that's not adjuvanted is higher than with an adjuvanted vaccine. ...

"For seasonal flu for kids under the age of 9, we currently use two different vaccine doses. So, it's very likely that, at least for kids, two doses are going to be required, but only time will tell."