Liberia is now free of Ebola after no new cases were reported in 42 days, twice the maximum incubation period for the deadly disease, the World Health Organisation (WHO) has announced.
However, new cases emerged this week in neighbouring Sierra Leone and in Guinea, the other two countries hit hardest by the worst Ebola outbreak in history.
Each country recorded nine new cases in the week ending May 3, according to the WHO's latest situation report.
Officials and survivors said they are cautious about openly celebrating the end of Ebola in Liberia, as the continued presence of the disease in the region means just one sick patient slipping over the border into Liberia could spark a resurgence of cases.
Peter Jan Graaff, the UN secretary-general's acting special representative and head of the United Nations Mission for Ebola Emergency Response, said: "We're proud of what we collectively managed to do but we need to remain vigilant.
"The virus is not yet out of the region and as long as the virus is in the region we're still all of us potentially at risk."
President Ellen Johnson Sirleaf toured health centres in Monrovia on Saturday, embracing and taking group photos with health workers. She was accompanied by US ambassador Deborah Malac.
The WHO has recorded more than 4,700 Ebola deaths in Liberia, more than in any other affected country. There have been more than 11,000 deaths in West Africa.