Six D.C. postal workers opt for anthrax vaccine

WASHINGTON (CNN) -- Only six employees at Washington's Brentwood mail processing facility have elected to receive an experimental anthrax vaccine as of Thursday, just over two months since the building became a focal point of the anthrax crisis, said the Centers for Disease Control and Prevention.

In October, health officials urged 2,000 workers at Brentwood to undergo screening for infection to the bacteria after two of their colleagues died from inhalation anthrax.

Letters addressed to Senate Majority Leader Tom Daschle and Sen. Patrick Leahy and containing potent anthrax spores passed through the postal facility, authorities said.

Virtually all Brentwood employees took a 60-day course of antibiotics in case they were exposed to the bacteria. With the course now complete, the CDC offered the workers 40 additional days of the antibiotic and the vaccine.

The vaccine, normally a preventive measure, is considered experimental because it now being given after exposure to anthrax. It will be given in three doses over a four-week period.

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Although tests with animals have shown anthrax will not likely occur more than 60 days after the subject was exposed to the bacteria, "traces of live spores have been detected in the lungs up to 100 days following exposure," said a CDC statement dated December 18.

While only a handful of Brentwood workers have decided to take the vaccine as of Thursday night, postal workers retain the option to take it through January 7.

With their initial 60-day antibiotic course now over, 106 Brentwood workers have opted to end all medical treatment and continue medical counseling only, the CDC said. Another 74 will continue antibiotic therapy.

-- CNN's Dave Adhicary contributed to this report.