Tests May Lead to Alternative Smallpox Vaccine

By Chris Schneidmiller
Global Security Newswire

WASHINGTON — Tests performed on monkeys and mice could lead to an alternative smallpox vaccine to protect humans unable to take existing inoculations, according to articles being published tomorrow in two scientific journals (see GSN, Feb. 20).

The United States has acquired enough smallpox vaccine to protect all U.S. residents in case of a terrorist attack, but its use could cause health trouble for up to 20 million people who suffer from suppressed immune systems, heart disease or skin problems such as eczema, according to researchers.

The existing vaccine contains a reproducing pox-type virus that stimulates the immune response, said researcher Bernard Moss of the National Institute of Allergy and Infectious Diseases. While healthy people generally recover quickly from the infection, the virus could continue to replicate and harm those with serious health trouble.

Even coming into close contact with a person who received the existing vaccine could be dangerous for someone whose immune system has been weakened by AIDS, an organ transplant or other health problems, Moss said (see GSN, Feb. 13).

However, Moss and his fellow researchers found a modified version of the vaccine developed more than 30 years ago protected “immunocompromised” mice from the pox virus while such mice eventually died after receiving an existing vaccine. In another study, researchers determined that monkeys treated with the modified virus became immune to monkeypox, which is similar to smallpox in humans.

The modified vaccine would require a higher dose than the existing version because the new version is “attenuated,” meaning it does not reproduce. That feature, however, makes the vaccine safer to administer to those who are vulnerable to the existing treatment, Moss said.

Further testing must be done on humans, which could take years. If the results are positive, the new vaccine would be submitted to the U.S. Food and Drug Administration for licensing.

“It would mean a feeling of more security for those people who would be at risk for the present vaccine,” Moss said. “There would be a vaccine for them,” he added.

Details of the virus study on monkeys will be published tomorrow in Nature magazine, while the article on the mice research will appear in the online edition of Proceedings of the National Academy of Sciences.

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