By Evan Bush

The Seattle Times

University of Washington researchers, in partnership with a Seattle biotech company, say they have developed a promising candidate for vaccination against the virus that causes COVID-19.

The researchers on Monday published a peer-reviewed paper in Science Translational Medicine that shows their vaccine induced a strong immune response in mice and macaque monkeys, a key step toward human trials.

“We’re very excited about the results and seeing our vaccine entered into the pipeline,” said Deborah Fuller, a microbiologist whose UW Medicine lab developed the potential vaccine. “It’s not going to be one vaccine that’s going to knock down this pandemic.”

The RNA vaccine produced an antibody and T-cell response after a single dose in both young and old mice, as well as in the macaques, said Fuller, an author on the Science Translational Medicine paper.

The strong response to the vaccine by non-human primates suggests it could work with people, too.

“Doses and vaccines and vaccine immune responses that work well in monkeys, translates well in humans,” Fuller said.

The vaccine could offer several advantages over others that research groups around the world are pursuing, as scientists race to produce a formulation that will be protective against the virus that causes COVID-19.

The researchers believe their approach, which relies on replicating RNA, could immunize with lower doses and fewer doses in comparison to other vaccines in development.

Because older mice showed strong immune response, the researchers also think older people could benefit from this formulation where other vaccines fail to produce a sufficient immune response.

The vaccine could be scaled up with relative ease, the researchers said. RNA vaccines typically combine with lipids, or fatty acids. The combination process can create manufacturing challenges, said Jesse Erasmus, the paper’s lead author.

The researchers partnered with a Seattle company, HDT Bio Corp., to create a two-part formulation that would allow the separate manufacture of RNA and lipid particles, which could speed manufacture.

The compounds could be mixed at bedside, Erasmus said.

The researchers continue to monitor the monkeys that have received the vaccine.

“The study began a little over 100 days ago. We plan to monitor them continuously through August. The plan is to enter them into a challenge study to see if the durability of the immune response is challenged,” Erasmus said.

The challenge trial would expose the monkeys to the virus that causes COVID-19 some five to six months after the vaccine dose was administered. That will allow researchers to test the durability of the vaccine’s immune response.

HDT Bio has taken steps toward garnering FDA approval for phase one human trials, Erasmus said.

“The plan is to begin trials later this summer,” Erasmus said.

In phase one human trials, researchers would try to determine an optimal dose of the vaccine with a study of about 40 to 50 people.