One of the poorest nations in the world, the former French colony was the host for "patient zero" - an infant who became the first victim - and health authorities went on to record some 2,500 deaths.
"Today the World Health Organization (WHO) declares the end of Ebola virus transmission in the Republic of Guinea," the UN agency said in a statement in Geneva.
British Ebola nurse recovers again, leaves specialist hospital unit
The fever spread stealthily and terrifyingly from December 2013, striking two neighbouring countries, Sierra Leone and Liberia, with sporadic cases also in Mali, Nigeria and Senegal.
As world health watchdogs struggled to respond, the death toll mounted at a dizzying rate, igniting fears in Europe and elsewhere of a virus that transgressed borders and national controls.
Around 11,300 people died out of almost 29,000 recorded cases, according to a WHO tally that many experts believe greatly understates the real impact of the outbreak.
It was the deadliest epidemic of Ebola since the disease was first identified in 1976.
The last known case in Guinea was a three-month-old named Nubia, who was born with the disease but whose recovery was confirmed on November 16.
That triggered the countdown to the announcement, as a period of 42 days -- twice the virus's maximum incubation period -- is required to declare a country free of transmission.
"It's the best year-end present that God could give to Guinea, and the best news that Guineans could hope for," said Alama Kambou Dore, an Ebola survivor.
"From 2013 to 2015, Guineans suffered, they lived and survived, they endured, they were stigmatised, rejected, even humiliated because of this disease, which leapt out of nowhere."
WHO declares end of Ebola outbreak in Sierra Leone
The WHO declared Sierra Leone' epidemic over on November 7, triggering wild celebrations in the capital Freetown. On December 3, Liberia released its last two known Ebola cases from hospital, starting the six-week countdown.
President Alpha Conde is expected at an official celebration in Conakry on Wednesday, flanked by representatives from donor countries and dozens of organisations, from Doctors without Borders to the Red Cross, that were frontline responders in the crisis.
Guests will pay tribute to the 115 health workers who died fighting Ebola and eight members of an Ebola awareness team killed by hostile locals in Guinea's forested southeast.
A range of top African musicians, including Youssou N'Dour and Mory Kante, will take to the stage for a "memorial" concert -- entitled "Bye-bye, au revoir Ebola" in the francophone country.
Amid the jubilation and hope for a return to normality, experts have sounded a note of caution, as the virus has been shown to persist in the sperm and other body fluids of survivors significantly longer than previously thought.
Liberia was declared free of human-to-human transmission in May and again in September, but both times the fever resurfaced in small clusters.
"We have to be very careful because, even if open transmission has been stopped, the disease has not been totally defeated," said Alpha Seny Souhmah, a Guinean health technician and Ebola survivor.
Guineans battling Ebola have been faced with huge obstacles, not least the country's grinding poverty and a crumbling medical infrastructure.
Frontline workers have also had to combat the rumour mill, entrenched denial, fear of Ebola stigma and resistance to confinement measures deemed authoritarian or unreasonable.
They also had to persuade people to abandon funeral traditions whereby mourners touch the body of their loved one -- a potent pathway to infection.
The epidemic devastated the economies of the worst-hit countries, as crops rotted in the fields, mines were abandoned and goods could not get to market.
Two new Ebola cases in Guinea, WHO says
Strong recent growth has been curtailed in Guinea and while Liberia has resumed growth, Sierra Leone is facing a severe recession, according to the World Bank, which has mobilised $1.62 billion for Ebola response and recovery efforts.
The bank's group president Jim Yong Kim called for continued support for Guinea and its neighbours, vowing to "do everything we can to help these countries and the world prevent another deadly pandemic".
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