AKIPRESS.COM - Last week, the Lancet medical journal published a study showing a vaccine distributed in Guinea was 100 percent effective in protecting against Ebola, Irish Sun says.

But could the study be trusted?

The gold standard for clinical studies includes a group that receives the treatment, a group that receives nothing but regular care, and a third group that receives a placebo.

Given the ethical considerations, and the lives at risk, there was no control group, and no one received a placebo in the Guinea study. The focus was on preventing more deaths from a disease that had already killed more than 11,000 people in West Africa.

Questions surrounding the Lancet study explain why another study newly released by the U.S. National Institutes of Health will be welcomed by scientists and health care workers trying to end the epidemic that raged through three West African countries and threatened others.

Scientists at NIH conducted a study with macaque monkeys that showed a single dose of the vaccine provided 100 percent protection against the Ebola virus. That was when the monkeys received the vaccine seven days before being exposed to Ebola. If the monkeys received the vaccine three days before exposure, they were still partly protected.

This was the same vaccine people in Guinea received, VSV-EBOV. It contains a weakened live virus (VSV) that carries a protein from an Ebola virus. The result is a safe vaccine that does not make healthy people sick.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases at NIH said: "That means that you can use the vaccine late in the course of an outbreak, which is important, because that's when you might want to use it. The other thing that was important was that it was able to protect against the multiple variants of the Ebola virus that are circulating."

There are four different strains of Ebola virus. The one that's been circulating in West Africa is the deadly Zaire strain. Each of the four strains has different variations. This vaccine protected against the variations of the Zaire strain.

The World Health Organization said there were only two confirmed cases of Ebola reported in the past week: one in Guinea, the other in Sierra Leone. It's the lowest weekly total since March 2014 and the third consecutive decline in weekly case incidence.

The report doesn't mean that Ebola is going away. The WHO is still concerned that people exposed to the virus are out there.