DALLAS (AP) — As Thomas Eric Duncan’s health deteriorated, nurses Amber Joy Vinson and Nina Pham were at the Ebola patient’s side.

They wore protective gear including face shields, hazardous materials suits and protective footwear as they inserted catheters, drew blood and dealt with his body fluids. Still, the two somehow contracted Ebola from the dying man.

As health officials try to figure out how that happened, the nurses’ cases have brought new scrutiny to national Ebola protocols that had never before been put to the test at a general hospital. Authorities are examining whether those guidelines need to be rewritten.

The federal Centers for Disease Control and Prevention protocols for Ebola recommend that nurses use personal protective equipment such as gloves, goggles, face shields and fluid-resistant gowns — as Vinson and Pham did. They also recommend diligent cleaning and disinfection of any items containing contaminated materials.

CDC director Dr. Tom Frieden has cited a “breach in protocol” that allowed Pham to be infected while she cared for Duncan in the intensive care unit, but has not specified the nature of that breach. He did however note that some of the nurses at Texas Health Presbyterian Hospital inadvertently violated the CDC protocols by wearing too much protective gear.