BioEd Online

A skin patch could save lives lost to influenza by boosting the response to vaccination in elderly people. The technology is entering clinical trials in Europe.

Of the half a million or so people killed each year by flu, the vast majority are aged 65 or over. The annual flu vaccination gives them only meagre protection, because it does not fire up their flagging immune systems.

The booster patch, which is being developed by IOMAI in Gaithersburg, Maryland, resembles a large sticking plaster pasted over the skin puncture left by the jab. It contains a toxic protein extracted from the bacterium Escherichia coli, which commonly causes food poisoning.

When delivered to immune cells in the skin, however, the toxin acts as an 'adjuvant', giving the immune system an extra kick. The body reacts more strongly to the vaccine and becomes better armed to fight off a future encounter with the flu virus.

The company's latest results, published in the Journal of Virology, show that the patch bumps up the response to a flu jab in elderly mice. Animals given the patch produced up to 50 times more infection-fighting T cells than those who received the jab alone¹.

The company has already tested the patch in over 50 elderly people in Switzerland, says Larry Ellingsworth, vice-president for research at IOMAI. The results are not published yet, but Ellingsworth says they are promising. Another trial on a younger group started late last month. "I'm very optimistic," Ellingsworth says.

The skin patch might also be used to boost the response to other types of vaccination, says immunologist John Clements of Tulane University in New Orleans, Louisiana, who advised the company during its development. Other groups with substandard immune systems, such as young children or those with HIV, might also benefit from the patch, the makers hope.

Nasal sprays

In the United States, doctors recommend that everyone over the age of 65 have the flu jab. The elderly fall victim to the virus when it infects the nose and lungs, allowing killer infections from other bugs, such as pneumonia, to take root.

Many other research groups are seeking ways to enhance the influenza vaccination for the elderly, using a range of different adjuvants and ways to deliver them. Some are adding them directly to the vaccine; others are wafting them up the nose.

Some vaccines already contain adjuvants. The idea of using the E. coli toxin has been around for several decades, but was temporarily abandoned because it triggers a strong and dangerous immune reaction when it is added to the vaccine, swallowed or sprayed up the nose. Applying it to the skin prompts a milder reaction, says Ellingsworth.

"It's a good idea," says Roy Jennings who studies flu vaccination at the University of Sheffield, UK. But he believes that it may be necessary to find an adjuvant that can be delivered direct to the nose, where the real battle against the flu virus takes place. "I don't think they've hit it," he says.