The materials are of particular interest to congressional investigators, in part because the U.S. Department of Homeland Security is pushing for a revamping of BioWatch that would cost taxpayers $3.1 billion in its first five years. Last week, Homeland Security issued a draft request for proposals and announced that it would host a related "industry day" for prospective contractors.
A spokeswoman for Sebelius said the department was reviewing the letter.
The scientists' firsthand assessments of BioWatch are known to diverge from those voiced by representatives of the Department of Homeland Security, who have repeatedly denied the existence of any false alarms or other serious deficiencies.
From the time BioWatch was launched in 2003, the CDC has acted as liaison with public health laboratories nationwide that help operate the system. In the event of a BioWatch alarm for the presence of anthrax, smallpox or other deadly pathogens, the CDC would also be responsible for deploying vaccines, antibiotics or other medicines from the U.S. Strategic National Stockpile.
BioWatch now operates in more than 30 major cities, where air samplers are located atop buildings and in other public places, continuously sucking air through dry filters. Once every 24 hours, the filters are taken to local public health labs to be analyzed for traces of any of the pathogens.
When President George W. Bush unveiled BioWatch in his January 2003 State of the Union address, he said it would "protect our people and our homeland" against a germ attack by terrorists. He called BioWatch "the nation's first early-warning network of sensors to detect biological attack."
In July, the Energy and Commerce Committee began investigating BioWatch's performance in response to a report by the Los Angeles Times that described serious shortcomings, including dozens of false alarms and confidential government tests showing that the system could not be relied on to detect an actual attack.
The article also revealed that CDC officials had told White House aides at a meeting on Nov. 21, 2011, that they would not release emergency medicine in response to a BioWatch alarm unless the presence of a pathogen was confirmed by follow-up sampling and analysis.
Citing the Times article, the congressional committee on July 19 wrote to CDC Director Thomas Frieden, requesting names of the CDC officials who had attended the White House meeting, plus agency documents "showing whether the BioWatch program or any test used by the BioWatch program can accurately detect traces of dangerous pathogens."
The committee's staff conferred subsequently with Dr. Toby L. Merlin, who heads the CDC's division of preparedness and emergency infections, about instances when BioWatch has failed to distinguish between benign, "near-neighbor" organisms and pathogens that can kill. Merlin, who is a pathologist, said he considered such an event a "false positive," the committee noted in a Nov. 13 letter to the CDC director.
The letter also requested that the CDC turn over a broad range of "documents ... relating to BioWatch" possessed by either Merlin or an agency colleague, senior microbiologist Stephen Morse. Morse and Merlin had represented the CDC at the November 2011 White House meeting, according to people familiar with the matter.
The letter to Sebelius on Thursday pointed to a Dec. 22 Times article that it said raised additional concerns about BioWatch, "especially the question of how best to protect public health."
"Prompt production of these documents from HHS is needed," said the letter, "to help the committee proceed with this inquiry with the benefit of the CDC's expertise and knowledge in this area."