He spent much of the 1990s studying HIV and vaccines. As chief of infectious diseases at the Washington Hospital Center, he had worked on preparations on what to do should there be an intentional release of an infectious agent. This came into operation when following the September 11 attacks of 2001, stockpiles of antibiotics were ready for the subsequent anthrax attacks. He later devised a staging system for inhalation anthrax and advocated the stockpiling of chest drains for its treatment should toxic fluid accumulate around the lungs.