"The saddest part about this is that there were so many doses administered," Miller said. "(Meningitis) takes up to a month to a month and a half to develop. We've got patients who may have been exposed who are literally waiting to see if anything happens. As a pharmacist, that really upsets me personally, and it upsets my entire profession."

On Wednesday, Massachusetts Gov. Deval Patrick accused the NECC of misleading regulators and operating outside its license by shipping large batches of drugs nationwide.

And the state pharmacy board took the step of requiring all compounding pharmacies in Massachusetts to sign affidavits stating they are complying with state regulations requiring compounders to mix medications for specific patients.

With so many questions still unanswered, the public's worries about allergy shots, flu shots and other prescription medications are understandable, Miller said.

Unfortunately, this kind of contamination could happen with any drug -- manufactured or compounded. Yet the vast majority are perfectly safe, Miller said, and patients shouldn't avoid a needed medication out of fear. However, he said, patients should feel free to ask their doctor or pharmacist: Where does this drug come from?