Friday, March 28, 2014

Don't hit me with your best shot: self-vaccination against the flu

Well, we may be ramping down flu season up here in the northern hemisphere (if winter EVER decides to go away!), but the idea of self-vaccination against the flu is interesting nonetheless, and will be useful in the future as it continues to develop.

Seasonal flu is an infectious disease caused by a virus, and it is estimated to affect 5-10% of adults, and 20-30% of children.  The seasonal flu causes 3 to 5 million cases of severe illness annually (that's globally, fyi), and up to 500 000 deaths.  The most effective way to avoid getting the flu and spreading it to others is through vaccination.  Now, the way flu vaccines work, is that organizations like the CDC and WHO monitor what flu strains are going around.  While the northern hemisphere is experiencing its flu season, the southern hemisphere is not, and vice versa.  That means that whichever flu strains are going around the southern hemisphere in July are being monitored to try to predict which flu strains will be going around the northern hemisphere in January.  This process involves hundreds of research labs, all testing and identifying flu viruses from infected patients world-wide, year-round.  The WHO then consults with experts on which strains should be covered in the next flu shot.

Vaccination coverage against the flu is actually not as high as they should be, and the reason is not that flu shots are dangerous, but that a lot of people have trouble finding the time (I'm guilty of that this year...).  In the US, annual influenza vaccination coverage hovers around 42%, and in Europe it's about 12% for the general population.  To address low coverage and the costs of annual flu shots, researchers from Atlanta, led by James Norman, hypothesized that microneedle patches could be used to get people to vaccinate themselves.  This may sound like a weird concept, but keep in mind that when you take over-the-counter or prescribed medication in your own home, you are self-administering your medicine.  This self-vaccination would be the same thing.  This is what a microneedle patch looks like:

These have been used before for cosmetic applications and for hormone delivery, but data generally is not available.  This paper reports a study on the usability and acceptability of these patches for self-vaccination.

All participants were shown how to use the patch, and then self-administered three separate times.  The researchers found that there was a learning curve to self-administering, with the number of insertion sites increasing each time the patches were used.  The insertions were also generally well-tolerated, with only very mild redness and swelling of the skin.  About 51% of the participants who regularly get flu shots said they would be vaccinated against influenza if given the choice of having a microneedle patch instead of a needle and syringe.  Of the participants who don't get flu shots, 30% expressed willingness to be vaccinated if they were offered a microneedle patch, which went up to 38% when they were given the choice to self-administer their vaccine.  That means that almost 1/3 of normally non-vaccinated people would get one with this new method!  Participants were asked to rate the pain level between the use of a microneedle patch and an injection using a needle and syringe.  Microneedle patches scored 10 times lower on the pain scale!  

The most significant predictors of vaccine uptake were beliefs about the convenience and reliability of microneedles, and support for microneedles from doctors and family.  Ultimately, the researchers found that the use of microneedles could improve vaccination coverage in the US from 42% to 65%, which could have a significant impact on reducing hospital admissions, productivity losses, and deaths.  

Obviously this technology isn't ready to be rolled out for the 2014 flu season, but it's an interesting start and could have significant implications in the near future.

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