A vaccine, but no needle.

Since the start of the pandemic, plans to vaccinate against Covid-19 using patches have multiplied, testifying to a movement that could well revolutionize the way vaccines will be administered in the future.

The technique will be able to avoid a few bursts of tears for some children, who are not very fond of syringes.

But above all, it has many other advantages, particularly in terms of distribution, or increased efficiency.

A study in mice, published Friday in the journal Science Advances, found promising results.

The patch used: a 1cm by 1cm square, made of plastic, with over 5,000 tiny peaks on its surface, "so small you can't even see them", described Dr David Muller, co-author of the study and virologist at the University of Queensland, Australia.

These tips have been coated with the vaccine, which is deposited on the skin when it penetrates it.

Improved efficiency

Mice were vaccinated with the patch (applied for two minutes), and others with needles.

For the first, "we obtained a very strong antibody response, including in the lungs, which is important for Covid-19", detailed the researcher.

The results obtained have largely "surpassed" needle vaccination, he says.

Secondly, the efficacy of a single dose was evaluated.

By using an adjuvant, which serves to stimulate the immune response, the mice are then “not at all sick.” Vaccines are usually given by intramuscular injections.

But the muscle does not present "many immune cells, required to support the vaccine", compared to the skin, explains Dr. Muller.

In addition, the insertion of the tips causes tiny injuries, which alert the body of a problem and thus stimulate the immune response.

For the scientist, the advantages of the technique are clear: first, the vaccine can remain stable for a month at 25 ° C, and a week at 40 ° C (compared to a few hours at room temperature for the vaccines from Pfizer or Moderna ).

This allows less dependence on the cold chain, which constitutes "a challenge for developing countries".

Ease and quantity

In addition, “it's incredibly easy to administer”: no more need for trained nursing staff.

Burak Ozdoganlar, professor of engineering at Carnegie Mellon University in Pittsburgh in the United States, has also been working on these patches since 2007.

And he sees another benefit: "a smaller amount of vaccine, delivered precisely to the skin, can produce an immune response similar to an intramuscular injection," he says.

An important factor as countries fight over doses.

He can produce 300 to 400 patches per day in his laboratory, but regrets not being able to test the messenger RNA vaccines from Pfizer or Moderna with, because he is not authorized to do so by these groups.

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