LC16m8 is a live attenuated smallpox vaccine that is produced in cell culture from vaccinia virus that has been attenuated, or modified, so that it can initiate an immune response without causing serious adverse effects. It has been licensed in Japan since 1980.
"The preliminary study results are consistent with the far larger Japanese experience," Dr. Richard Greenberg of the Kentucky School of Medicine, told the 2005 American Society for Microbiology Biodefense Research Meeting. "LC16m8, an attenuated smallpox vaccine, has had a 100 percent take rate and has been well tolerated -- intensive monitoring for myopericarditis has not uncovered any cardiac toxicity in the first 66 volunteers."
"Take rate" is a measure of a smallpox vaccine's effectiveness in producing an immune response.
The only smallpox vaccine licensed for use in the United States is made from unattenuated vaccinia virus and it has been associated with potentially fatal encephalitis and heart inflammation.