"We are very excited that today Uganda has received 1,200 doses of one of the three candidate vaccines against the Sudan Ebola virus," Uganda's Health Minister Jane Ruth Aceng told AFP after the plane carrying the shipment touched down at Entebbe airport.
Ministry spokesman Emmanuel Ainebyoona said this first delivery contained doses from the Sabin Vaccine Institute.
The WHO said three vaccine candidates are to be used; one by the University of Oxford and Serum Institute of India, another by the Sabin Vaccine Institute and a third by Merck & Co Inc.
They will be used in a so-called ring vaccination trial, where all contacts of confirmed Ebola patients, and contacts of contacts, are jabbed along with frontline and health workers.
The World Health Organization's regional director for Africa, Matshidiso Moeti, told reporters on Thursday that Uganda had "begun the countdown to the end of the Ebola outbreak".
She hailed the arrival of the vaccines as "a promising step towards possible protection against the virus".
According to WHO criteria, an outbreak of the disease ends when there are no new cases for 42 consecutive days -- twice the incubation period of Ebola.
"There are 33 more days" to declare the end of the outbreak, said Yonas Tegegn Woldemariam, WHO representative in Uganda.
Last week Uganda said it had discharged its last Ebola patient from the hospital, raising hopes for the end of an outbreak of the deadly hemorrhagic fever declared on Sept. 20.
There are currently no licensed vaccines for the Sudan strain of the virus that caused the infections in Uganda, although there are several candidate vaccines that appear to be suitable for evaluation, the World Health Organization says.
Existing vaccines combat the more common Zaire strain, which spread during recent outbreaks in the neighboring Democratic Republic of Congo.
Ebola causes vomiting, diarrhea, and bleeding from all body orifices, and spreads through contact with the bodily fluids of those infected.
This report was prepared with data from Reuters and Agence France-Presse.