ATLANTA (AP) – About one in 10 doctors who vaccinate privately insured children are considering dropping that service largely because they are losing money when they do it, according to a new survey.

A second survey revealed startling differences between what doctors pay for vaccines and what private health insurers reimburse: For example, one in 10 doctors lost money on one recommended infant vaccine, but others made almost $40 per dose on the same shot.

The survey was revealing even to some doctors. "Many physicians really weren't aware and that they were getting reimbursed so little," said Dr. Gary Freed of the University of Michigan, a co-author of both articles published in the December issue of the journal Pediatrics.

The studies are the first to attach numbers to doctors' long-simmering complaints that they are only breaking even – or even losing money – when they give shots. "It's a pleasure to see a real study to show we're not just making this up," said Dr. Herschel Lessin, a paediatrician in Hopewell Junction, New York who said his practice's spending on vaccines has more than doubled from 2006 to 2007.

Experts say there's no evidence that significant numbers of doctors are quitting the vaccination business yet because of financial concerns.

But health officials are worried. Reimbursement concerns were behind an exodus of doctors from vaccine programmes in the 1980s, which contributed to a terrible resurgence of measles in 1989-91 that caused 11,000 hospitalisations and 123 deaths.

This year, US measles cases rose to the highest level in more than a decade, mainly because some parents are opting out of getting their kids vaccinated.

Health officials fear that problem, along with doctor's economic concerns, could set the stage for bigger outbreaks in the future.

"This is a very important wake-up call," said Dr. Lance Rodewald of the US Centers for Disease Control and Prevention, referring to the two new studies.

The first study was based on a mail-in survey last year of nearly 1,300 paediatricians and family physicians; nearly 800 responded.

About half said they had delayed buying at least one vaccine because of the cost.