Skin patch may strengthen flu vaccine - conference
WASHINGTON, May 10: A skin patch designed to boost the immune response may help stretch out scarce supplies of influenza vaccine at the start of a pandemic, researchers at a small US company said.
The patch is coated with diarrhea-causing E coli bacteria, a strain known as enterotoxigenic E. coli or ETEC, formulated to pass into the skin. These stimulate the immune system and, in theory, strengthen the immune response to the vaccine.
Tests on mice and guinea pigs showed using the patch allowed a much smaller dose of vaccine to be used than normal to stimulate an immune response, Dr Gregory Glenn, chief scientific officer at Iomai Corporation, said yesterday.
Animals given vaccines against either seasonal influenza, or the H5N1 avian influenza vaccine, required a much lower dose -- 100 to 10,000 times lower -- to get the same immune response if patches were stuck to their skin than without the patch, Glenn said.
''We hope that would translate in humans to 10- to 50-fold (lower),'' Glenn said in a telephone interview.
Glenn presented his findings to a meeting in Baltimore sponsored by the National Foundation for Infectious Diseases.
''We have data showing you can attach a patch at the time of injection,'' Glenn said. ''Instead of putting on a Band-Aid, you put on the patch. We are activating the skin's immune system.'' Glenn, whose company is discussing testing the patch as part of H5N1 vaccine trials at the National Institute of Allergy and Infectious Diseases, said the patches could be made now and distributed ahead of a pandemic.
''You can stockpile it well in advance. It not going to be dependent on the strain (of influenza),'' he said. ''You could have 600 million patches sitting there in the US''
The H5N1 avian flu virus, which has swept across Asia, Europe and into Africa in just months, still mainly affects birds. But experts say it poses a great risk of evolving into a form that can easily pass from person to person. If it caused a pandemic, vaccines would be the best defence but a closely matched vaccine cannot be made until an actual pandemic strain occurs, because influenza is such a mutation-prone virus.
There are not enough vaccine factories in the world today to make the amount of vaccine needed to protect the population so government and corporate experts are trying to stretch vaccine doses to allow more people to be vaccinated. Iomai's is a unique approach, said Dr. Bruce Weniger of the US Centres for Disease Control and Prevention.
''It's a fascinating new technology,'' Weniger, a vaccine expert, said in a telephone interview from the conference. ''It seems to be very simple to apply.'' The company also makes the patch as a vaccine against traveller's diarrhea, which Glenn says has been shown in Phase 2 studies to be safe in people. The patch as an influenza adjuvant may not be tested in people for some time -- unless a pandemic develops, Glenn said.
He said the patch stimulates antigen-presenting cells in the skin called Langerhans cells, which travel to the nearby lymph nodes to produce a sustained immune response.
Iomai has applied for US Health and Human Services Department contracts for the vaccine. Last week, HHS announced 1 billion dollars in contracts to five companies develop new and better influenza vaccines, and to make them on US territory.