The drugmakers say that a mid-stage clinical trial of an Alzheimer’s vaccine has been suspended while they look into a potentially serious side effect suffered by one patient in the study, Reuters reports. Dosing in the study of the experimental vaccine, ACC-001, was halted after the patient was hospitalized with skin lesions from what the physician serving as lead researcher suspected was a case of inflammation of blood vessels.

“Following discussion with the FDA, all further dosing has been suspended while this particular event is fully evaluated,” Jonathan Birt, an Elan spokesman, tells Reuters. The drugmakers are in talks with health regulators and the physician to further understand the clinical and scientific issues, Birt adds.

The patient, meanwhile, has been released from the hospital and the lesions are healing, he says. Elan, though, stresses the vaccine and study has no connection to bapineuzumab, its lead Alzheimer’s drug candidate, which is also being developed with Wyeth and is in late-stage clinical testing.