Thirty-year-old smallpox vaccine compares well to modern equivalent

An attenuated smallpox vaccine developed over 30 years ago in Japan recently did well when compared to a conventional vaccine developed in the United States.

The study, published in the Journal of Infectious Diseases, examined phase I and II clinical trials of an attenuated vaccine known as LC16m8, according to CIDRAP News.

LC16m8 is made from the vaccinia virus, but is weakened by the removal of a protein called B5R. It was tested exclusively in Japan, where it was also used to inoculate a small group of military personnel.

The U.S. double-blind trials used 154 young adult volunteers who were randomly assigned to receive either LC16m8 or the conventional vaccine Dryvax. The volunteers were then monitored to see the strength of their immune response and whether there were any adverse effects.

The two groups showed similar local and systemic reactions to the vaccines, CIDRAP News reports. Immunogenicity testing showed positive results in generating antibodies against vaccinia, variola and monkeypox viruses.

The attenuated vaccine showed strong cellular immune responses that were reportedly higher than the Dryvax responses in one measure, but lower in another.

Overall, the vaccine was considered to be well-tolerated and cited for potential in protecting individuals against smallpox. Further study is recommended in the report.