Medical practice

'Painless' flu vaccine skin patch shows promise

"A 'painless' sticking plaster flu jab that delivers vaccine into the skin has passed important safety tests in the first trial in people," BBC News reports. Results of a small phase 1 trial were encouraging, with no serious side effects reported.

The patch, around the size of a standard plaster, contains 100 "microneedles" – tiny needles containing the vaccine, which then dissolve after delivering a dose.

The trial including 100 people in the US and aimed to see whether the patch was safe and tolerable and may be able to deliver flu vaccine as effectively as an injection.

People who had the patch found it less painful, but were more likely to get redness and itching where the patch had been applied.

There were signs that the patch was just as effective as standard injection in terms of antibody response, but larger studies will be needed to confirm this.

Aside from being less painful, another benefit of the patches is that they don't require refrigeration. This means that they could conceivably be posted to people. They may also be ideal for countries in the developing world where access to reliable refrigeration is often limited.

However, we need to see bigger trials to confirm that the vaccine patch works and is safe. Even if the results are confirmed, it's likely to be several years before flu vaccine patches are in routine use.

Where did the story come from?

The study was carried out by researchers from Emory University in the US and was funded by a grant from the National Institute of Biomedical Imaging and Bioengineering.

The study was published in the peer-reviewed journal The Lancet. Several of the researchers work for or have financial interests in the company that produced the vaccine patch, Micron Biomedical.

BBC News, The Guardian, the Daily Mail and the Daily Telegraph all welcomed the end of "painful" injections with the "pain-free jab". They provided a mostly accurate and balanced overview of the study, but only BBC News mentioned the "mild" side effects of redness, soreness and itchiness reported by people using the patch.

What kind of research was this?

This was a phase 1 randomised controlled trial with four groups.

Researchers wanted to assess the safety and tolerability of the flu vaccine patch compared to the standard intra-muscular injection and a placebo patch (dummy treatment).

They also wanted to compare the self-administered patch with the patch administered by a healthcare professional.

Phase 1 trials are the earliest stage of a randomised controlled trial (RCT) that primarily aims to see whether a new treatment is safe to use.

They can give an indication of whether the treatment works (for example, this study also looked at antibody response) but that's not the main aim. If the results are promising they can then be followed by subsequent trials in a larger number of people to confirm the treatment is safe and to get better data on how effective it is compared with other treatments.

What did the research involve?

Researchers recruited 100 people aged 18 to 49 who'd not had a flu vaccine that year. They divided them randomly into four groups:

  • 25 were given the standard flu vaccine given by a healthcare professional by intramuscular injection (which is currently the standard way the vaccine is given to adults)
  • 25 were given the flu vaccine by a healthcare professional using a microneedle patch
  • 25 were given a placebo vaccine by a healthcare professional by microneedle patch
  • 25 self-administered the flu vaccine by microneedle patch

The flu vaccines – both injection and patch – contained three influenza viral strains given in the 2014/15 seasonal vaccine (H1N1, H3N2 and B vaccine strain).

The main outcomes the researchers looked at were the number of serious adverse effects up to 180 days after the vaccine was given and local skin reactions to the patch up to a week later. The researchers also asked people which method they preferred.

Other (secondary) outcomes were to look at the effects of the vaccine, which the researchers checked by taking blood to look at antibody levels after 28 days.

Usually in RCTs, people are "blinded" to which group they're in. In this study, people couldn't be blinded to whether they had the patch or the injection, but they didn't know whether they had the placebo vaccine or the real one.

Also, the scientists who checked their blood test and unwanted effect results didn't know which type of vaccine the participants had been administered.

The study wasn't designed to be big enough to see whether the patch was more effective than the injection, only to see if it was at least as effective.

In a separate study, researchers tested how well the vaccine survived in patches stored at a range of temperatures for a year.

What were the basic results?

No-one in the study had a serious adverse reaction to the vaccine, either by injection or the patch. There were no flu-like illnesses or no new chronic illnesses reported.

The overall number of adverse events was similar between the injection and patch groups, and between the group given the patch by a healthcare-professional and the group who applied the patch themselves. But there were differences in the type of adverse effect.

Seven days after vaccination, people who had the injection were more likely to say they had felt pain at the vaccine site – 44% of those who had the injection compared to 20% of those who had the patch.

However, people who had the patch were more likely to say they had experienced itching (84% compared to 16%), redness (40% compared to none) or tenderness (68% compared to 60%).

The antibody response to the vaccine was similar between people who had the injection or the patch, regardless of whether they had it given by a healthcare professional or administered it themselves. However, the antibody response with the injection and the patch was not significantly greater than with the placebo patch for some vaccine viral strains. This could have been because of a high level of background immunity to certain flu virus strains, the researchers said.

Everyone in the self-administration group successfully administered the patch, and results for all the patch groups showed that the needles had dissolved into the skin.

Of the participants who had the patch, 70% of them said they preferred it to other administration methods such as injection or nasal spray.

In a separate test, researchers found the vaccine patches could be stored for a year at temperatures ranging from 5C to 40C without the vaccine losing its potency. The vaccine used for injections has to be refrigerated.

How did the researchers interpret the results?

The researchers say their results "provide evidence that microneedle patch vaccination is an innovative new approach with the potential to improve present vaccination coverage and reduce immunisation costs."

They say that in future, flu vaccination could be self-administered in medical clinics, workplaces or at home, and that because the patches are not temperature sensitive and can be thrown away in general household waste, they could be posted to whole populations, in the event of a flu pandemic.


Further testing in larger trials needs to be done to be sure these initial results hold true and that the vaccine patch is safe and effective. This is the first time these flu microneedle patches have been tested on humans, and the study was relatively small, with only 100 participants.

But if the results are confirmed, this new method of delivering the flu vaccination could make a big difference. The patches could have several main advantages over traditional injections:

  • they may be preferred by people who dislike needles and avoid vaccination because of the fear of pain
  • it may be quicker and easier to administer the vaccine yourself, than to make an appointment to have an injection
  • the patches don't leave dangerous "sharps" waste that has to be carefully disposed of
  • they don't have to be kept refrigerated, making it easier to store and distribute vaccines

While the idea of a "no injection" vaccine sounds great if you don't like injections, they may have a much bigger impact in parts of the world where it's difficult to reach and administer vaccines with a continuous cold chain, and where health care staff are in short supply.

This study is a good example of animal research that has successfully progressed through to human testing. Seven years ago the journal Nature Medicine published promising results of this flu vaccine patch tested in mice, which we discussed at the time.

Now it looks as if this has the potential to become one of the rare treatments that does progress through all testing stages to become a new licensed treatment.

However, more studies are needed to be sure this delivery method is safe and effective. It's unlikely we'll see flu vaccines patches on pharmacy shelves for a few years yet.

NHS Attribution