Merck & Co. and NewLink Genetics stopped their early-stage Ebola vaccine trial after only a week, after four of 59 volunteers said they had pains in their hands and feet, according to a report from The Financial Times.

The study was the first of three phases of clinical trials typically required for regulatory approval. The trial may restart in January, if the joint pains patients experienced are "benign and temporary," The Financial Times said. Merck bought the vaccine last month for as much as $50 million from NewLink; it's one of several attempts to create a vaccine for the disease.

Meanwhile, the National Institutes of Health will be admitting a patient with Ebola exposure to a special clinic in Maryland. The patient is an American nurse, who was exposed to the disease in Sierra Leone; if the Ebola diagnosis is confirmed, this will be the fifth person who is diagnosed with Ebola in the US.