Congo-Kinshasa: Three New Ebola Vaccines Are Being Developed. An Infectious Disease Expert Explains

When it comes to Ebola outbreaks, it's not often we have two pieces of good news in one week.

First, we heard there's new funding of up to US$62 million to fast-track the development of vaccine candidates against the type of virus circulating in the Democratic Republic of the Congo (DRC) and neighbouring Uganda.

Then, we heard authorities had downgraded the confirmed numbers of Ebola deaths and cases in the region.

As of June 2 local time, DRC health authorities reported 344 confirmed cases, including 60 confirmed related deaths. Uganda has reported 15 confirmed cases, including one death. Previously, suspected cases in the region were more than 1,000.

Here's what we know about the three vaccine candidates announced this week and why we still have a long way to go before this concerning outbreak is under control.

Yes, we have two approved Ebola vaccines. One is Ervebo, the other Zabdeno/Mvabea.

Both are effective and approved for protection against the Zaire Ebola virus specifically. However, this is a different virus to the one circulating in the DRC and Uganda currently, the Bundibugyo Ebola virus.

Unfortunately, different types of Ebola virus have different surface proteins that the vaccine targets. This means existing vaccines against the Zaire virus aren't effective enough to be used against the Bundibugyo virus.

The newly announced funding, from the Coalition for Epidemic Preparedness Innovations, aims to fast-track the development of the first, approved human vaccine specific to the Bundibugyo virus.

This support includes facilitating clinical trials as quickly as possible so if a vaccine proves both safe and effective it will be available as fast as possible.

A World Health Organization (WHO) expert panel called this "the most promising candidate vaccine".

It's a single-dose vaccine that's being developed by the International AIDS Vaccine Initiative (or IAVI) with the University of Texas Medical Branch. It uses a similar approach to the approved Ervebo vaccine.

The vaccine candidate has been tested in macaque monkeys, where it was shown to protect against the Bundibugyo virus.

But it hasn't yet been tested in humans. The WHO expert panel said clinical trials were likely seven to nine months away.

This vaccine candidate is from the same United States-based pharmaceutical company that makes one of the approved COVID mRNA vaccines. The company also has an approved mRNA vaccine against respiratory syncytial virus, or RSV.

It's developing an mRNA-based vaccine targeting the surface glycoprotein of the Bundibugyo virus.

The company says