FDA panel to review Acambis's smallpox vaccine

A Food and Drug Administration panel will review a smallpox vaccine by Acambis PLC on Thursday.

Acambis, a British company with offices in Cambridge, has been making the vaccine for a US strategic stockpile since being awarded a contract in late 2001 amid concern about the possibility of a terrorism attack using the smallpox virus.

The vaccine is considered a second-generation vaccine and is made using cell-culture lines. It was derived from Dryvax, an older vaccine made by Wyeth.

Acambis said it is awaiting another grant from the government to keep making the vaccine, known as ACAM2000, but the contract depends on FDA licensing.

Members of the military are routinely vaccinated against smallpox, and the Acambis vaccine could also be used for that if approved.

The vaccine would not be sold commercially in the United States. Routine vaccination of US children stopped in 1972, and naturally occurring cases of the disease were eliminated in the 1970s after a global vaccination campaign. The last US case of smallpox was in 1949.

The virus causes a severe skin rash and is fatal in about 30 percent of cases.

The FDA said ‘‘there are serious safety concerns’’ associated with smallpox vaccines such as Dryvax and ACAM2000. ‘‘Traditionally recognized’’ serious side effects include rare cases of severe skin infections and myopericarditis, an inflammation of the heart-wall muscle and surrounding area. The side effects can be fatal. In clinical trials of the Acambis vaccine, there were no fatalities.

But the agency said one of the studies involving the vaccines suggested the rate of myopericarditis is higher than previously suspected. Ten cases of myopericarditis were seen in the studies and occurred with both vaccines.

‘‘However, the potential benefits of administration of ACAM2000 during a smallpox outbreak to persons who are determined to be at high risk of exposure or who have been recently exposed outweigh potential risks,’’ the FDA said.
(Dow Jones)