The U.S. Centers for Disease Control and Prevention said the number of lab workers who may have been exposed rose from the 75 people first disclosed on Thursday. As of early Friday, 32 staff were taking the powerful antibiotic ciprofloxacin, or Cipro, and 20 were taking another antibiotic called doxycycline, CDC press officer Benjamin Haynes said in a statement.
In addition, as many as 27 people were getting the anthrax vaccine to prevent infection. No illnesses have been reported, but the agency expects more people to step forward now that news of the anthrax scare is public. The agency did not give reasons why other workers were not taking medication.
The safety breach, which originated in the CDC's bioterror lab, raised new concerns about the way laboratories around the world conduct research into the deadliest known pathogens, from anthrax to Ebola and avian flu.