A health care worker with a recent history of treating Ebola patients in West Africa, and who was quarantined, has tested negative for the disease in a preliminary test, the New Jersey Department of Health announced Saturday.

The patient arrived at Newark Liberty International Airport on Friday. The individual had no symptoms upon arrival, but later developed a fever while quarantined at the airport. The New Jersey Department of Health said the patient was transferred from the airport’s quarantine station to Newark’s University Hospital for “evaluation and isolation.”

Doctors at the hospital “continue to monitor the patient and consult with the Department of Health and the CDC on patient evaluation and any potential need for additional testing,” it said, adding that the individual will remain “under mandatory quarantine for 21 days and will be closely monitored by public health officials.”

After a Doctors Without Borders physician tested positive for Ebola in New York City on Thursday, New Jersey and New York officials enacted a new, stricter policy for all medical workers arriving at airports in those two states from Ebola-affected countries. They now face additional screening measures, and will be automatically quarantined.

Starting on Monday, new federal guidelines dictate that all travelers from West African countries affected by Ebola will be monitored for 21 days upon entering the United States.

In his weekly address published Saturday, President Barack Obama described the measures that the government is taking to respond to Ebola cases in the U.S., as well as in West Africa where the virus has now killed nearly 5,000 people.

“We have to be guided by the science, by the facts, not fear,” Obama said.

Additional reporting by Brian Ries