Now researchers in Germany say that the rapidly vibrating tattoo needle could be a useful way of delivering vaccines under the skin instead of insoluble ink.

In studies with mice, tattooing a vaccine produced 16 times more antibodies than a simple injection into muscle tissue.

The level of antibodies indicates the strength of the immune system's response.

Dr Martin Mueller, one of the researchers behind this work, says that the greater damage to the body caused by the tattoo needle may explain the better immune response.

Merck & Co. said Friday that it is ending enrollment and vaccination of volunteers in the study, which was partly funded by the National Institutes of Health.

It was a high-profile failure in the daunting quest to develop a vaccine to prevent AIDS. Merck's vaccine was the farthest along, considered the most promising and was closely watched by experts in the field.

Officials at the company, based in Whitehouse Station, N.J., said 24 of 741 volunteers who got the vaccine in one segment of the experiment later became infected with HIV, the virus that causes AIDS. In a comparison group of volunteers who got dummy shots, 21 of 762 participants also became infected.

"It's very disappointing news," said Keith Gottesdiener, head of Merck's clinical infectious disease and vaccine research group. "A major effort to develop a vaccine for HIV really did not deliver on the promise."

Current flu vaccines focus on two proteins on the surface of the virus. However, these constantly mutate in a bid to fool the immune system, making it impossible for vaccine manufacturers to keep up with the creation of each new strain.

The universal vaccines focus on a different protein called M2, which has barely changed during the last 100 years.

The protein is found in all types of Influenza A, including the current bird flu and the virus that caused the 1918 Spanish flu pandemic which killed up to 50 million across the globe.

Normally, such vaccines would have to go through at least five years of human tests before going on the market. However, if a bird flu pandemic occurs before that, they could be made more quickly available.

Zurich-based Cytos, which is also developing anti-smoking and obesity vaccines, has showed that its version of the jab stops mice dying from a dose of flu strong enough to kill them four-times over.

Early tests of skin-patch vaccines are beginning in hundreds of volunteers, one version designed to protect against the flu and another to prevent travelers' diarrhea.

The idea isn't just pain-free vaccination. The National Institutes of Health is helping fund patch research in hopes of strengthening today's imperfect flu shots, and gaining extra help if bird flu or some other super-flu ever triggers a pandemic.

Indeed, patch developer Iomai Corp. proposes that the mailman, not a doctor, deliver flu vaccine during a pandemic. Once a vaccine is brewed, simply ship patches to people's homes with instructions to slap one on.

Doctors might not like the go-it-alone method. But the technology's main promise may be in developing countries. Unlike syringe-based vaccines, patches wouldn't need refrigeration — nor pose the infection risk of reused needles, a continuing problem.

Scientists are reporting Friday that the vaccine was 100% effective in preventing cervical cancer and precancerous changes tied to two types of a common sexually transmitted virus.

"It's a very impressive finding," Christopher Crum, director of women's and perinatology pathology at the Brigham and Women's Hospital in Boston, said Thursday.

A team from the University of Pennsylvania School of Medicine has shown that by using a cancer vaccine based on the bacterium Listeria monocytogenes, they can cure mice with established breast tumors. Cancer vaccines, which are more properly described as immunotherapy, work by boosting an immune response against tumor-associated antigens. Using Listeria, the researchers, led by Yvonne Paterson, PhD, Professor of Microbiology, delivered the tumor-associated antigen HER-2/Neu to immune cells. HER-2/Neu is overexpressed in 20 to 40 percent of all breast cancers and also present in many cancers of the ovaries, lung, pancreas, and gastrointestinal tract. These cells eventually enlist killer T cells to seek out and destroy the tumor cells that display the HER-2/Neu molecule.

"We found that we can stop the tumor from growing out to 100 days, at which time we stopped measuring since this is a long time for experiments of this type," says Paterson. "The tumors stopped growing or went completely away." The researchers published their findings in the September 15 issue of The Journal of Immunology.

"It took a while to dissect what elements of an immune response were best able to cause the rejection of established tumors," she says. "But in the last couple of years it has paid off and we are very excited to see the technology finally being tested in cancer patients. The dream of the cancer immunotherapist is to provide an alternative and more humane way of controlling metastatic disease than current chemotherapies."