The 42-day risk period for contracting fungal meningitis from tainted steroid injections ended on Wednesday, since the drugs were recalled on Sept. 26, but new case reports will probably continue to trickle in.
Cases could continue to show up for at least a few months, said Dr. Tom Chiller, a fungal disease expert at the Centers for Disease Control and Prevention told ABC.
With 18 new cases reported last Friday, and abscesses causing even fungal meningitis survivors to go back to the hospital with new symptoms, sighs of relief could be premature.
"Forty-two days is not a magic number by any sense of the word," said Chiller, who is the deputy chief of the CDC's Mycotic Diseases Branch. "This is a moving target. The outbreak is evolving."
The CDC publicized the 42-day period as a way for individual physicians to determine whether putting all at-risk patients on anti-fungal medications was a good idea, Chiller said. Since anti-fungal medicine can cause liver and kidney damage, there was a risk it could do more harm than good. The long risk period would mean a long anti-fungal regimen.
A CDC analysis revealed that while preemptive anti-fungal prescriptions reduced patients' risk of death or stroke from meningitis by .1 percent, they increased the risk of other adverse health problems by up to 14 percent, Chiller said.
Chiller said this kind of fungus, exserohilum rostratum, can have a very long incubation period. Although the median incubation period so far has been 20 days, the longest incubation period went beyond 100 days, he said.
"One of the important things to add is that we do feel pretty confident that the further out you are from injection, the lower the risk," Chiller said. "When that risk becomes zero, we don't know."
So far, 409 fungal meningitis cases, including 30 deaths, have been reported to the CDC this fall. In addition, 10 people who received the shots to other parts of their bodies came down with fungal joint infections. Fungal meningitis, a deadly disease that causes inflammation of the membrane surrounding the brain and spinal column, is not spread from person to person.
Up to 14,000 people received the tainted injections produced at New England Compounding Center in Framingham, Mass, which recalled all products and shut down on Oct. 6. It is now being investigated by the Food and Drug Administration, even though its oversight usually falls under its state's pharmacy board's jurisdiction.
It's not clear how the fungus got in the steroid vials, but an FDA investigation revealed that a quarter of the steroid vials in an NECC bin contained "greenish black foreign matter," according to an FDA form released Oct. 26. The form went on to identify several clean rooms -- where sterile products are produced -- that had either mold or bacterial overgrowths.
Signs that the CDC believes new cases will taper off include the CDC's new, more relaxed online case reporting schedule. Instead of updating case counts by state every day at 2 p.m., as it had for the last month, the CDC will update Monday, Wednesday and Friday only. This Monday's steep new case count of 15 was actually only five new cases per day.
However, 18 new cases were reported between Thursday and Friday of last week, according to CDC reports. Case counts only reached 18 or higher on four days of the whole outbreak.