NEW YORK (Reuters) - The first person quarantined under strict new rules in the New York City area for people with a high risk of Ebola tested negative, New Jersey officials said on Saturday, as President Barack Obama said the response to the deadly disease needed to be based on "facts, not fear".

Under the new policy, anyone arriving at the two international airports serving New York City after having contact with Ebola patients in Liberia, Sierra Leone or Guinea must submit to a mandatory 21-day quarantine.

The requirement exceeds current federal guidelines, although the Obama administration is discussing similar measures.

"We have been examining the protocols for protecting our brave healthcare workers, and, guided by the science, we'll continue to work with state and local officials to take the necessary steps to ensure the safety and health of the American people," Mr Obama said.

The disease has killed thousands of people in West Africa and has become a political issue in the United States ahead of Nov 4 congressional elections.

The new rules in New York and New Jersey were announced a day after an American doctor who recently helped Ebola patients in Guinea also tested positive for the virus at Manhattan's Bellevue Hospital.

The doctor, who was self-monitoring, started feeling symptoms about a week after he returned home.

The first person to face the mandatory quarantine under the new rules was a medical worker who arrived at Newark Liberty International Airport on Friday after treating Ebola victims in West Africa.

She broke into a fever soon after being quarantined and was taken to University Hospital in Newark, New Jersey's health department said.

Tests on the woman, who has not been publicly identified, showed no signs of the virus, the health department said on Saturday.

Even so, she remains under the 21-day quarantine.

She was described by friends as a nurse who went to Sierra Leone to help with the epidemic, the Newark Star-Ledger reported.

The worst Ebola outbreak since the disease was identified in 1976 has killed almost half of more than 10,000 people diagnosed with the disease - predominantly in Liberia, Sierra Leone and Guinea - although the true toll is far higher, according to the World Health Organization.

The United Nations agency also said on Friday that trials of Ebola vaccines could begin in West Africa in December, a month earlier than expected, and hundreds of thousands of doses should be available for use by the middle of next year.