Dreaded vaccinations one day could be as simple as sticking on a Band-Aid — ouchless and do-it-yourself.
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.
Only time will tell if the patches really work. Iomai is in initial stages of human testing, and years of additional work are required for proof. But previous research does suggest the skin could provide an improved route to rev up the immune system, perhaps allowing doctors to use lower vaccine doses.
"It may be that the expectations for vaccine patch technology are now slowly bearing fruit," says Dr. William Schaffner of Vanderbilt University, a vaccine expert who has long monitored the field.
"It is what I would call an alluring technology."
If it works against one disease, a patch likely could be tweaked to deliver numerous kinds of vaccines. Iomai also has Defense Department funding to help develop an anthrax vaccine patch.
"The approach is novel and may be the way many vaccines are given in the future," says Dr. Herbert DuPont of the University of Texas Health Sciences Center in Houston. A specialist in diarrheal diseases, he is helping Iomai test the travelers' diarrhea patch in U.S. tourists headed for Mexico.
Most of today's vaccines are shots into muscle. But doctors have long known that getting vaccine just inside the skin is deep enough. History's first crude inoculations, against smallpox, merely involved scratching pus from a related but milder virus into the skin. And recent research using small needles to push flu vaccine just inside the skin found lower doses could be as protective as full-strength muscle shots.
The question is how to do skin vaccination without actually breaking the skin. Patches frequently deliver medications, such as nicotine or birth control. But drugs are very small molecules that can fairly easily penetrate skin to reach the bloodstream. Vaccines typically contain much larger proteins.
Iomai's method, discovered by one of its founders at the Walter Reed Army Institute of Research: Just get past a thin outer layer of dead skin to the epidermis, the first living skin layer. There, specialized cells called Langerhans cells can recognize a pathogen and speed to the lymph nodes to alert the immune system.
In Iomai's laboratory in Gaithersburg, Md., outside Washington, CEO Stanley Erck demonstrates: He brushes his skin with a gadget bearing a bit of sandpaper, like the kind used for filing fingernails. The round patch then is stuck to the scuffed spot for several hours.
"We're not inventing anything new, just exposing pathogens the way humans have seen them all their life," Erck says.
Now come the tests:
- Furthest along are patches designed to protect against an E. coli strain called ETEC, a leading cause of travelers' diarrhea. DuPont's study aims for up to 300 participants to spend at least two weeks in Mexico or Guatemala, visiting pre-specified clinic sites there if they do get diarrhea to see if the patch failed or if the culprit was some other germ.
In an initial challenge study at Johns Hopkins University last year, patch recipients who drank the bacteria suffered significantly less diarrhea than their unvaccinated counterparts, Erck said.
- Last month, Iomai began first-stage testing of flu vaccine patches in 270 volunteers, to track the patches' safety and whether recipients develop as many flu-fighting antibodies as those given standard flu shots.
- Another goal is immune-stimulating patches to boost a vaccine's effects. The elderly are less protected by today's flu shots than young people. And studies of bird-flu vaccine show that a huge dose will be required regardless of age, unless immune-boosters can help stretch supplies.
Iomai's travelers' diarrhea patch also seems to give the immune system a general boost. In a small study last year, giving elderly volunteers that patch plus a standard flu shot spurred a greater immune response than the shot alone. The company now is preparing a larger study, and competing for a government contract to add immune-boosting patches to a federal stockpile of flu pandemic supplies.
"There definitely is promise to that idea," says Dr. David S. Cho of the NIH's flu product development office, who monitors the patch project — although he cautions that Iomai must prove if the immune booster works with a variety of flu strains.