The US has made provisions to stockpile an additional 3.42 million doses of BioThrax, a vaccine used to protect against anthrax, indicating continued fears over a terrorist attack despite the death of al-Qaeda leader Osama bin Laden.

Emergent BioSolutions announced that it has signed a modification to its current procurement contract with the US Government to supply the doses of BioThrax in the third quarter of this year.

Company chairman and CEO Fuad El-Hibri said, “This contract is an indication that BioThrax remains a critical component of the Government’s arsenal of biodefense medical countermeasures.

“In addition to this contract modification, we are continuing discussions with the US Government regarding a follow-on procurement contract, which we anticipate will cover a multi-year period.”

In 2001, anthrax attacks occurred in the US over the course of several weeks, beginning one week after the September 11 attacks.

Letters containing anthrax spores were mailed to several news media offices and two Democratic US senators, killing five people and infecting 17 others.

This modification to the contract is valued at up to $101m for the delivery and shipping of additional doses.

Delivery of these doses will commence immediately following early completion of final delivery of the 14.5 million doses of BioThrax under the original contract.

Anthrax is an acute disease caused by the bacterium Bacillus anthracis.