A little after 5 p.m. on Thursday, Connecticut public health officials breathed a sigh of relief as preliminary test results for the Yale graduate student who had been admitted to Yale-New Haven Hospital exhibiting Ebola-like symptoms came back negative. Five days later, the Yale researcher is still under quarantine — and will remain so for another 16 days.

Although the test came back negative, President Salovey said in a Thursday email that the researchers would continue their quarantine for 21 days, in adherence with guidelines established by the state of Connecticut. Director of Yale Health Paul Genecin said the decision to continue the quarantine came from the commissioner of the Department of Public Health Jewel Mullen ’77 SPH ’96 in accordance with Gov. Dannel Malloy’s Oct. 7 state order declaring a public health emergency in Connecticut.

The hospitalized researcher and his companion have returned home for their 21-day quarantines, said Yale School of Medicine Dean Robert Alpern. The School of Public Health has not made either of the researchers’ names public.

Dean of the Yale School of Public Health Paul Cleary said he did not want to comment on the condition of the researchers in order to maintain their privacy. YNHH spokesperson Mark D’Antonio added that the hospital has no new information to share on the status of the researcher.

According to new Connecticut guidelines established after Malloy declared a state of emergency, the department may quarantine anyone who the commissioner reasonably believes has been exposed to or infected with the Ebola virus.

The Yale doctoral student admitted to YNHH last week was the state’s first test in rolling out the new guidelines. The patient was quarantined in the hospital, and placed in a negative pressure room to prevent the spread of contaminated air out of the room, according to Alpern. Alpern described the latter measure as “overkill,” and added that negative pressure isolation is only necessary if the disease is airborne. The Ebola virus can only be spread by direct contact with bodily fluids of people who are symptomatic.

Potential loopholes in the Ebola tests necessitate the quarantines, Alpern said. Two tests exist to detect Ebola; one measures viral RNA, an important genetic material, and the other measures antibodies, markers of the body’s immune response. Both tests may come back negative in the early stages of the infection if the virus has not grown to sufficient quantities to be detected.

Twenty-one days is a safe length of time, Alpern said, noting that most patients develop symptoms of Ebola earlier.

“I think it’s erring on the side of being too careful, because we’d rather be too careful,” he added.

Recent debates have surrounded Drexel professor of environmental engineering Charles Haas’s Oct. 14 paper in PLOS — a scientific journal — claiming that a 21-day quarantine is insufficient. However, Alpern said that he trusts that the Centers for Disease Control and Prevention are competent to decide the proper protocol.

The decision by the state of Connecticut to quarantine the researchers comes after the University decided not to quarantine the researchers when they returned from Liberia. Before the researchers’ return, the School of Public Health had announced that the researchers had agreed to self-sequester themselves for 21 days. But just over a week ago, Cleary announced that the researchers would not be quarantined.

Alpern said the change in decision was a judgment call based on CDC recommendations that state that unless a person shows Ebola-like symptoms or has come into contact with an infected person, quarantine is unnecessary. Although the researcher did come into contact with NBC reporter Ashoka Mukpo fewer than 24 hours before he became symptomatic with Ebola, Alpern said neither of the students were at risk of contracting the disease, and the latest decision is solely to “play it safe.”

In an Oct. 16 report in the New England Journal of Medicine, the World Health Organization Ebola Response Team stated that 95 percent of Ebola cases in the first nine months of the current outbreak showed symptoms within 21 days.