THURSDAY, companies May 11 (HealthDay News) — If and when a bird flu pandemic occurs, experts estimate there will be only enough vaccine to protect one in every 10 Americans.

Now, an essay in the May 12 issue of Science is heating up the debate on who that lucky 10 percent should be.

Countering the federal government’s policy of placing the elderly near the top of the list, two medical ethicists from the National Institutes of Health (NIH) say that after doling out the vaccine to essential health workers, people between 13 and 40 years of age should be next in line to receive the shot.

“What we are arguing is that younger people have more of their life to lead, and they ought to get higher priority,” explained Dr. Ezekiel Emanuel, chairman of the department of bioethics at The Clinical Center, which is part of the NIH.

He and co-author Dr. Alan Wertheimer stress that their opinion piece does not represent any official stance on the issue by the NIH, but they do hope it widens the debate on what could one day prove to be a very divisive issue.

The H5N1 avian flu virus continues to spread worldwide, infecting more than 200 people so far in bird-to-human transmissions and killing half that number, mostly in Asia. The big fear for health officials everywhere is that the virus could someday mutate so it passes easily from human to human. Just such an event sparked the 1918 flu pandemic, which killed more than 50 million people worldwide.

Two U.S. bodies — the National Vaccine Advisory Committee (NVAC) and the Advisory Committee on Immunization Policy (ACIP) — have helped craft the nation’s flu vaccine allocation strategy in the event of a pandemic. Everyone on the panels agreed that vaccine production staff and health-care workers should get top priority for any vaccine. Then were people at high risk for death or hospitalization due to preexisting health conditions, as well as pregnant women, and a few key government leaders.

The question of who should be next was tougher.

“You have to decide what the number one priority is, and we felt that that priority was saving lives and decreasing hospitalizations,” said ACIP chairman Dr. Jon Abramson, who is also chairman of the department of pediatrics at Wake Forest University Baptist Medical Center, in Winston-Salem, N.C.

According to Abramson, that means doling out vaccine to those people deemed at highest risk of dying should they become infected. With the lone exception of the 1918 pandemic — in which young adults were most at risk — “it is mainly the elderly and those with underlying cardiopulmonary and other chronic conditions that are most at risk” in flu pandemics, he said.

With that in mind, NVAC/ACIP submitted their allocation plan prioritizing the elderly to the White House, which accepted it. “We’ve never been asked to come back and rethink it,” Abramson said.

But Emanuel hopes that might change. In their essay, he and Wertheimer say that while the focus on “saving the most lives” does have merit, other considerations come into play. “On reflection, most people have the intuition that you should save children and young adults,” Emanuel noted.

This student loan calculator reasoning is based, in part, on something called the “life-cycle principle.” That states that people in late middle- and old-age have already had the opportunity to live through most of life’s stages of growth and experience, while adolescents and young adults are only beginning to do so.

Then there’s a concept the ethicists call “investment.”

“People in their late teens/early 20s should get priority because [society] has already invested a lot in them, and they are just on the cusp of leading their lives,” Emanuel said. “It’s precisely for these reasons that the death of a young person always seems m