Flu vaccine delivered through skin patches containing microneedles has proven
just as effective at preventing influenza in mice as intramuscular, hypodermic
flu immunization. A team of researchers at Emory
University and the Georgia Institute of Technology believes the new microneedle
skin patch method of delivering flu vaccine could improve overall seasonal vaccination
coverage in people because of decreased pain, increased convenience, lower cost
and simpler logistics over conventional hypodermic immunization.
 | | Image shows an array of microneedles against a microscope image. Photo: Gary Meek |
The research will be published in the Proceedings of the National Academy
of Sciences (PNAS). Another study by the research team on a different influenza
strain was described in the journal PLoS ONE.
The patches used in the experiments contained an array of stainless steel microneedles
coated with inactivated influenza virus. The patches were pressed manually into
the skin and after a few minutes, the vaccine coating dissolved off within the
skin. The coated microneedle immunizations were compared to conventional intramuscular
hypodermic injections at the same dose in another group of mice.
The researchers found that the microneedle vaccinations induced strong immune
responses against influenza virus that were comparable to immune responses induced
by the intramuscular, hypodermic immunizations. One month after vaccination,
the researchers infected both groups of mice with a high dose of influenza virus.
While all mice in a control group of unvaccinated mice died of influenza, all
mice in both the hypodermic and the microneedle groups survived.
"Our findings show that microneedle patches are just as effective at protecting
against influenza as conventional hypodermic immunizations," says Richard
Compans, PhD, Emory professor of microbiology and immunology and one of the
paper's senior authors. "In addition, vaccine delivery into the skin is
desirable because of the skin's rich immune network."
Even though cutaneous immunization has been shown to induce a broad range of
immune responses, and to be especially effective in individuals over age 60,
this method has not been widely used because it has not been convenient and
has required highly trained personnel.
"Unlike conventional hypodermic injections, microneedles are prepared
in a patch for simple administration, possibly by patients themselves, and inserted
painlessly onto the skin without specialized training," says Mark Prausnitz,
PhD, professor in the Georgia Tech School of Chemical and Biomolecular Engineering
and co-senior author. "These micron-scale needles can be mass produced
using low-cost methods for distribution to doctors' office, pharmacies and,
possibly, people's homes."
Other advantages of the microneedle patches could include more convenient storage,
easier transportation and lower dosage requirements. Lower doses could be particularly
important because flu vaccine production capacity sometimes is limited for seasonal
vaccine, and a future influenza pandemic would require much greater production
of vaccine.
Replacing a hypodermic needle with a microneedle patch also could significantly
impact the way other vaccines are delivered, and could be particularly beneficial
in developing countries. A microneedle patch could fit inside an envelope for
delivery by the postal service and would occupy much less storage space. Patches
also would increase vaccine safety by reducing the dangers of accidental or
intentional hypodermic needle re-use.
The project team plans future immunization studies in other animal models,
including guinea pigs or ferrets, before initiating studies in humans. Also,
more studies are needed to determine the minimum vaccine dose needed for full
protection.
The Emory and Georgia Tech research team began developing the new microneedle
vaccine patch technology in 2007 using grants from the National Institutes of
Health (NIH). The project team has extensive experience in microneedle development,
influenza vaccines, vaccine delivery systems, product development and interdisciplinary
collaboration.
In 2007 the NIH awarded a $32.8 million, seven-year contract to Emory, along
with the University of Georgia, to establish the Emory/UGA Influenza Pathogenesis
and Immunology Research Center. The center is working to improve the effectiveness
of flu vaccines through a number of different projects studying how influenza
viruses attack their hosts, how they are transmitted, and what new immune targets
might be identified for antiviral medicines.
Prausnitz and his colleagues have been working since the mid 1990s to develop
microneedle technology for painless drug and vaccine delivery through the skin.
The Georgia Tech team has also developed manufacturing processes for microneedle
patches and tested the ability of the needles to deliver proteins, vaccines,
nanoparticles, and other small and large molecules through the skin.
Other authors of the papers are Emory microbiologists Ioanna Skountzou and
Chinglai Yang, and first authors Ling Ye, Qiyun Zhu, Dimitrios Koutsonanos,
and Maria del Pilar Martin from Emory and Vladimir Zarnitsyn from Georgia Tech.
Other authors and contributors were Yulong Gao, Lei Pan, and Zhiyuan Wen from
Emory, and Harvinder Gill and Sean Sullivan from Georgia Tech.
Posted April 27th, 2009
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