If you had the option to administer the vaccine, would you rather use a needle or a skin cream? I thought so. The latter may soon be a viable option, as Stanford scientists have used a topical cream to powerfully vaccinate mice against tetanus.

The key is a bacteria that is almost certainly living on your skin right now: Staphylococcus epidermidis. It is thought to be mostly harmless, but in previous research the team found that it triggers a strong immune response in people. It appears to be a preventive defense against the microbe entering the bloodstream through everyday cuts and scrapes that damage the skin.

“We received blood from human donors and found that their circulating levels of antibodies were directed towards it S. epidermidis were as high as anything we routinely vaccinate against,” said Michael Fischbach, lead author of the new study.

They first conducted experiments on mice, which don’t normally do this S. epidermidis on their skin. When it was swabbed on their heads, antibody levels against the bacteria rose to levels higher than those of regular vaccines over the next six weeks.

The team wondered whether this mechanism could be abused as a non-invasive vaccination method against more dangerous pathogens. They found that a protein called Aap on the surface of the bacterium is responsible for triggering antibody production, so the researchers tweaked it to read a tetanus toxin.

They repeated the experiment and gave some mice a tetanus-boosted version of S. epidermidisand others the normal kind. After a few doses on the skin over a period of six weeks, their antibody levels were tested, and sure enough, those who received the bioengineered bacteria showed extremely high levels of antibodies directed against tetanus.

The final test was to inject the mice with lethal doses of tetanus. All mice that received the bioengineered bacteria remained symptom-free. Even when they were given six times the lethal dose of tetanus, they survived. Now everyone is getting the natural version of S. epidermidis succumbed to the infection.

Even better, this mechanism appears to be applicable to a variety of pathogens. In another test, they swapped the tetanus toxin for diphtheria and found that it also triggered a strong immune response in mice. This could end up being a completely new delivery method for many types of vaccines, saving us more than the pain of the needle.

“We think this will work on viruses, bacteria, fungi and single-celled parasites,” Fischbach said. “Most vaccines contain ingredients that trigger an inflammatory reaction and cause a mild feeling of nausea. These bugs don’t do that. We assume that you are not experiencing any inflammation at all.”

As fascinating as the research is, it is important to note that it is still early days. The next step is to test it on monkeys, the team says, and if that works, human clinical trials would begin in two or three years.

The research was published in the journal Nature.

Source: Stanford University