Smallpox Vaccine to Carry Heart Warning -- US

WASHINGTON (Reuters) - Wyeth's smallpox vaccine will come with a new "black-box warning" about cardiac problems that have occurred after immunization, the U.S. Food and Drug Administration said on Tuesday.

A black-box warning is the strongest type of warning for prescription drugs and vaccines in the United States.

The FDA said it approved a new warning that says cases of myopericarditis, a type of heart inflammation, have occurred after vaccination with Dryvax in healthy adults. The problem was reported in some patients in 2003, soon after the United States began a campaign to vaccinate health care workers against smallpox.

A Wyeth spokeswoman could not immediately be reached for comment.

Smallpox was eradicated in 1979, but some experts fear the infectious disease could reemerge in a biological attack. The infection kills about 30 percent of the time and leaves survivors with disfiguring scars.

The U.S. government has stockpiled tens of millions of doses of smallpox vaccine to be used in case of an attack.

Smallpox vaccination has been known to be risky, with experts estimating it can kill one out of about every million people immunized. New, safer smallpox vaccines are in development.

Information about the new warning for Dryvax was posted on the FDA Web site at http://www.fda.gov/cber/products/smalwye101105.htm.