A single shot of vaccine might soon be sufficient to provide protection against rabies, U.S. researchers reported on Friday.

Currently, the World Health Organization's (WHO) standard for rabies infection is post-exposure prophylaxis. The complex regimen usually requires six different shots over 28 days: five of the rabies vaccine and one of rabies immunoglobulin.

Now, a research team led by James McGettigan at Thomas Jefferson University says it has developed a new type of rabies vaccine, which just needs one single shot to induce a strong enough immune response.

In addition, the vaccine appears to be efficient in both pre-exposure and post-exposure settings.

The current standard vaccine is made from an inactivated rabies virus, whereas the experimental vaccine is made from a live rabies virus. The virus is modified by removing a gene called the Matrix, thus inhibiting its spread within the vaccine recipient.

The new vaccine has successfully induced a rapid and efficient anti-rabies immune response in mice and non-human primates, according to the researchers. Their study appears in the Journal of Infectious Diseases.

Worldwide, the annual number of rabies-related deaths is estimated to be 40,000 to 70,000. The disease is endemic in developing areas, where the six-shot post-exposure regimen is not feasible for many people due to cost and availability.

According to the WHO, approximately 10 million people worldwide receive the post-exposure regimen.

"Developing countries do not have the resources to vaccinate people six times after exposure, so many of these 10 million do not receive the full regimen," Dr. McGettigan said. "Therefore, simpler and less expensive vaccine regimens are needed."

(Xinhua News Agency September 20, 2009）