Needle-free vaccine patches soon

Effective vaccines, without a needle: Since the start of the Covid pandemic, researchers have doubled down on efforts to create patches that deliver life-saving drugs painlessly to the skin, a development that could revolutionize medicine.

The technique could help save children’s tears at doctors’ offices, and help people who have a phobia of syringes.

Beyond that, skin patches could assist with distribution efforts, because they don’t have cold-chain requirements -- and might even heighten vaccine efficacy.

A new mouse study in the area, published in the journal Science Advances, showed promising results.

The Australian-US team used patches measuring one square centimeter that were dotted with more than 5,000 microscopic spikes, “so tiny you can’t actually see them,” David Muller, a virologist at the University of Queensland and co-author of the paper, told AFP.

These tips have been coated with an experimental vaccine, and the patch is clicked on with an applicator that resembles a hockey puck. “It’s like you get a good flick on the skin,” said Muller.

The researchers used a so-called “subunit” vaccine that reproduces the spikes that dot the surface of the coronavirus.

Mice were injected either via the patch over the course of two minutes, or with a syringe.

The immune systems of those who got the patch produced high levels of neutralizing antibodies after two doses, including in their lungs, vital to stopping Covid, and the patches outperformed syringes. 

The researchers also found that a sub-group of mice, who were given only one dose of vaccine containing an additional substance called an adjuvant used to spur immune response, “didn’t get sick at all,” said Muller.

Easy to apply

What makes them more effective?

Vaccines are normally injected into our muscles, but muscle tissue doesn’t contain very many immune cells needed to react to the drug, explained Muller.

In addition, the tiny spikes cause localized skin death, which alerts the body to a problem and triggers a greater immune response. 

For the scientist, the logistical advantages couldn’t be clearer. 

First, when dry-coated on a patch, the vaccine is stable for at least 30 days at 25 degrees Celsius (77 degrees Fahrenheit) and one week at 40C (104F), compared to a few hours at room temperature for the Moderna and Pfizer vaccines.