Phase III clinical trials for Ebola vaccines are set to begin in the upcoming weeks. Health workers in the three worst hit African countries – Sierra Leone, Liberia and Guinea – will be offered the immunizations. Scientists and pharmaceutical manufacturers have been racing to stop the spread of the deadly virus since the World Health Organization declared it an emergency situation in August 2014.

If the vaccines are effective, two million shots could be manufactured in a matter of months.

Experts from around the world are meeting at the WHO headquarters to analyze data from the initial testing. They will also determine a plan for caring out Phase III clinical trials. The US National Library of Medicine explains the various clinical trial phases, describing Phase III as when a drug is “given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.”

The meeting will focus on three different trial designs that involve the most advanced vaccinations. This includes two vaccines from GlaxoSmithKline, a vaccine from a collaboration of NewLink Genetics and Merck, and a final vaccine, slightly less advanced than the others, from Johnson & Johnson and Bavarian Nordic.

Contrary to what you may think, the companies are not in competition. Dr. Matthew Snape of the Oxford Vaccine Group told the BBC: “We are not playing first past the post here. Having multiple vaccines progressing through clinical trials increases the likelihood of vaccine manufacturers having the capacity to meet production demands should mass immunization be required.” A serious concern considering over 22 million people are at risk.

While the media’s attention has waned on the Ebola crisis, the situation is still serious. Indeed, it may be getting worse. Reports from Liberia show that the disease is moving out of the capital city, Monrovia, and spreading to rural areas, some of which are extremely remote. The scattered cases make it difficult for epidemiologists to track the spread of the disease. While residents have become more welcoming to international aid workers, there are still many who harbor suspicions. The total number of Ebola cases is considered by many to be underreported.