FDA Approves New Smallpox Vaccine to Protect Against Bioterrorism
The U.S. Food and Drug Administration recently licensed a new vaccine to protect against smallpox, a highly contagious disease with the potential to be used as a deadly bioterror weapon. The vaccine, ACAM2000, is intended for the inoculation of people at high risk of exposure, such as first responders, to smallpox and could be used to protect individuals and populations during a bioterrorist attack.
ACAM2000 will be included in the Center for Disease Control and Prevention's (CDC) Strategic National Stockpile of medical supplies. Known stockpiles of the virus are kept only in two approved labs in the United States and Russia. CDC considers it a Category A agent, meaning it presents one of the greatest potential threats for harming public health.
"The licensure of ACAM2000 supplements our current supply of smallpox vaccine, meaning we are more prepared to protect the population should the virus ever be used as a weapon," said Jesse L. Goodman, M.D., M.P.H., director of FDA's Center for Biologics Evaluation and Research. "This vaccine is manufactured using modern cell culture technology allowing rapid and large scale production of a vaccine with consistent product quality."
Smallpox is caused by the variola virus, a virus that emerged in human populations thousands of years ago. It spreads through close contact with infected individuals or contaminated objects, such as bedding or clothing. There is no FDA-approved treatment for smallpox and the only prevention is vaccination.
A worldwide vaccination program eradicated smallpox in the population. The last case of naturally occurring smallpox in the U.S. was in 1949 and the last case in the world was reported in Somalia in 1977.
According to CDC, the symptoms of smallpox typically began with a high fever and head and body aches. A rash follows that spreads and progresses to raised bumps and pus-filled blisters that crust, scab, and fall off after about three weeks, leaving a pitted scar. The fatality rate historically was about 30 percent.
ACAM2000 is made using a pox virus called vaccinia, which is related to but different from the virus that causes smallpox. The vaccine, FDA says, contains live vaccinia virus and works by causing a mild infection that stimulates an immune response that effectively protects against smallpox without actually causing the disease. It is derived from the only other smallpox vaccine licensed by FDA, Dryvax, approved in 1931 and now in limited supply because it is no longer manufactured.
Although smallpox vaccination ended in the United States in 1972, the U.S. military resumed vaccination of at-risk personnel in 1999, after concluding that the disease posed a potential bioterrorism threat.
"Smallpox could be a particularly dangerous biological threat to us that would kill or debilitate a high percentage of the population," said Rear Adm. W. Craig Vanderwagen, M.D., assistant secretary for preparedness and response, U.S. Department of Health and Human Services. "The licensing of ACAM2000 will make us better prepared as a nation because it provides an important, effective tool for protecting first responders and individuals with a high risk of exposure from this potentially lethal disease."
ACAM2000 is manufactured by Acambis Inc. of Cambridge, England and Cambridge, Mass. Dryvax was made by Wyeth Laboratories Inc. based in Madison, N.J.