Uganda has begun a trial vaccination programme for the strain of Ebola viral infection that is behind the country's latest outbreak, according to the World Health Organization (WHO), while the number of confirmed cases has risen to three.

Last week, the east African country announced an outbreak of Ebola in the capital, Kampala, with a single case, a nurse who died on January 29.

The total number of cases have now risen to three, with the two additional cases from the family of the deceased man, Ministry of Health spokesperson Emmanuel Ainebyoona told Reuters late on Monday.

In a post on the X platform late on Monday, Matshidiso Moeti, WHO director for Africa, said Uganda had also started a clinical trial of a vaccine against the Sudan strain of Ebola.

Currently there is no approved vaccine for that strain. The existing vaccination is for the Zaire strain, which is behind a recent outbreak in the neighbouring Democratic Republic of Congo.

"This marks a major milestone in public health emergency response and demonstrates the power of collaboration for global health security," Moeti said. "If proven effective, the vaccine will further strengthen measures to protect communities from future outbreaks."

Bruce Kirenga, who heads Makerere Lung Institute, a research organisation that is doing the trial, told local media during the launch of the vaccination that it had been developed by the International Aids Vaccine Initiative (IAVI) and that the institute had received about 2 460 doses.

The health ministry last week said that the trial would target contacts of confirmed cases.

A high-fatality disease, Ebola infection symptoms include haemorrhage, headache and muscle pains. The virus is transmitted through contact with infected bodily fluids and tissue.