Story highlights

NEW: Nearly 800 in Guinea who'd been in contact with Ebola sufferers get experimental vaccine

NEW: A 30-year-old woman who died in a hospital in Monrovia, Liberia, had the virus, the WHO says

Liberia has twice before been declared Ebola-free -- in May 2015 and in September

CNN  — 

Two steps forward, one step back.

That’s the reality Friday in the fight against Ebola, with the World Health Organization announcing first that hundreds would get experimental vaccines in Guinea, then a short time later that the deadly disease has reemerged in Liberia.

All this comes days after the same international health body declared that the Ebola outbreak in West Africa was no longer a public health emergency of international concern.

This is still true, even given the new Liberia case. But that doesn’t mean Ebola is gone entirely, nor that it won’t rear its ugly head again.

“Flare-ups, at decreasing frequency, are expected,” the WHO noted in a tweet Friday.

Nearly 800 vaccinated in Guinea

No, this isn’t 2014, when Ebola was raging around West Africa, infecting tens of thousands of people and sending shock waves worldwide amid fears that it could spread.

Still, just because authorities managed to beat back the deadly virus doesn’t mean they’ve finished it off.

This became evident recently in southern Guinea, where seven of eight people infected with Ebola since late February died. The lone exception is an 11-year-old girl now in stable condition at an Ebola care facility in Nzerekore.

Health authorities, including some from the WHO, have put under medical observation about 1,000 people who’d been in contact with these eight people. They’re getting assistance like food, hygiene kits and cash.

And nearly 800 of them, including 182 “high-risk contacts,” got vaccinated over the past week, according to the WHO.

There had been a mad rush to produce Ebola vaccines two years ago, though there’s still no universally accepted one on the open market. Still, what has been administered in Guinea has been used before, having proved to be “highly effective in preventing Ebola infection in a large trial” conducted by Guinea, and having been used after a recent flare-up in Sierra Leone.

Liberia had been declared Ebola-free – twice

The Guinea cases were the first since that West African country was declared Ebola-free last December.

Liberia got the same designation before that, though it also knows how Ebola can come and go.

The latest example came Friday, with the WHO’s announcement that a 30-year-old woman who died the previous afternoon in a Monrovia hospital had Ebola.

It wasn’t clear how she got the disease or if others she knew are infected. Just in case, Liberia’s Health Ministry and partner agencies are trying to track down any people who’d been in close contact with her.

Along with Guinea and Sierra Leone, Liberia was the epicenter of the 2014 Ebola outbreak. It had more than 10,000 documented cases as well as nearly 5,000 related deaths, more than any other country, according to WHO statistics.

Liberia was declared free of Ebola in May 2015, only to have the deadly disease rear its head again in subsequent months.

In September, the WHO again made the same declaration after 42 days had passed since tests showed the last infected person no longer had the disease.