The World Health Organization is worried about the Ebola outbreak. The most recent 8 cases of Ebola have had no contact with anyone who had been infected with the virus previously.

The WHO said initial investigations into the cases by Uganda’s Ministry of Health had shown they were not contacts of people already known to have Ebola. “We remain concerned that there may be more chains of transmission and more contacts than we know about in the affected communities,” WHO Director-General Tedros Adhanom Ghebreyesus told reporters.

Uganda has also put the entire country on lockdown to prevent the spread, and people are still getting it. We should all hope Ebola was not engineered to become airborne.

Uganda Announces Ebola Lockdown

“Honestly, no one knows,” if Ebola can be transmitted via air, Dr. Maryam Keshtkar Jahromi, an infectious disease doctor and expert on viral hemorrhagic fevers from Johns Hopkins Medicine, said according to Yahoo News. 

While the CDC and WHO state that the virus is transmitted via bodily fluids and not via the air, there’s no proof that’s the case, she says, adding that running such an experiment would be very difficult due to the specialized equipment required.

There have been 60 confirmed and 20 probable cases since the outbreak began last month, and 44 deaths, the WHO said according to a report by Rappler. That’s a mortality rate of over 50% if we count probable cases.

The strain spreading in Uganda is the Sudan strain, and the existing vaccines and therapies do not work against it.

It all comes back to vaccines too, once again. The Ugandan government is collaborating with WHO to set up a trial of two vaccines in the early stages of development which do target the Sudan strain – one developed by Oxford University and the Serum Institute, and one made by the Sabin Institute in the United States, WHO confirmed.

While the danger to Americans is low, “the risk is not zero,” one infectious disease expert told Fortune according to Yahoo News. Dr. Keshtkar Jahromi said that there are currently no confirmed cases of Ebola in the United States, but healthcare workers should be on alert for signs and symptoms of the disease.