The current flu outbreak is the worst for young U.S. children in years, several experts say, perhaps worse in Western states than the Hong Kong flu of 1968-69.

A government epidemiologist and other disease doctors predict flu deaths among babies and toddlers will exceed the estimated 92 who die in an average flu year.

“We would expect that number would be higher in a season like this. It would be more than 92,” said Dr. William Thompson of the Centers for Disease Control and Prevention. “The question is how high. We can’t estimate that from our data.”

Even so, flu deaths among children are still rare. An average of 8,400 normally healthy children between 6 months and 24 months are hospitalized with the flu each year. The virus and its complications are the sixth-leading killer of children age 4 and under.

With the flu now widespread across half the country, large hospitals have already admitted hundreds of young patients, including a few critically ill in intensive care. Nearly all eventually get better, but the deaths have been particularly worrisome.

“What I am hearing anecdotally is this is a very, very bad season for children,” said Dr. Walt Orenstein, director of the National Immunization Program at the CDC.

So far, the CDC has learned of about three dozen deaths in children and teenagers. It is unclear how that figure compares to previous years because the agency doesn’t keep track of flu cases.

For the first season in four winters, the dominant flu strain is a so-called H3N2 virus, which is the most dangerous of the three main varieties of the bug. For that reason alone, experts say, the number of pediatric deaths will be higher than average.

The CDC estimates that in an average year, about 36,000 people — including 92 children under age 4 — die of the flu. However, the totals vary from year to year, depending on the strain that is circulating. Through the 1990s, the annual tally has ranged from 17,000 to 65,000. In a year when the more benign B-strain of flu dominates, just 24 deaths under age 4 are expected.

A reluctant Courtney Johannes, 5, gets a dose of FluMist from medical technician Al Vollman as she is held by her mother, Terri Johannes, left, at Pediatrics of Kempsville in Virginia Beach, Va. As vaccine injections are harder to find, more people are turning to the FluMist vaccine, which can be used on healthy children at least 5 years old.

Flu can be a serious disease for the young because they have not built up much natural defense against the virus. Most older children and adults can fight off severe illness, even if they get sick, because previous infections have strengthened their immune systems.

This year may be especially bad because many young children have never encountered an H3N2 virus. Making matters worse, this season’s virus is genetically different from the one that circulated in the late 1990s, so older children who had the flu then may not have very strong immunity.

Flu is most dangerous for youngsters who already have heart and lung problems, such as asthma, cardiac birth defects and lung damage resulting from prematurity.

However, doctors said they are especially concerned by reports of flu deaths among children who are otherwise healthy. In Colorado, where the first child flu deaths appeared, state officials said that at least four of the 11 young flu fatalities had no underlying diseases.

“The fact there are deaths among children without serious underlying health problems is very unusual,” said Dr. Robert Belshe of St. Louis University.

Dr. Paul Glezen of Baylor College of Medicine said colleagues across Texas tell him of flu-sick children filling their intensive care wards. “Not a lot are dying, but they are desperately ill,” he said.

At the University of Texas Southwestern Medical Center at Dallas, Dr. Jane Siegel said an otherwise healthy teenager was among three young flu deaths there this season. After getting the flu, he developed a severe bacterial infection, which is typically how the flu leads to death.

The hospital has treated 618 children with flu over the past two months, compared with 95 for the entire last season. Of these, more than a third were admitted to the hospital, and 5 percent were in intensive care.

In just one 12-hour period this week at Le Bonheur Children’s Medical Center in Memphis, 350 children with flu symptoms walked into the emergency department while 50 more came by ambulance and seven arrived in helicopters.

Dr. Andrew Pavia, chief of infectious diseases at Primary Children’s Medical Center in Salt Lake, said doctors there believe this is the biggest flu outbreak among children since 1968.

“There is no question there will be more deaths this year among children,” he said.