Over the past few months, the Rega Institute investigated eight candidate vaccines. Following trials on hamsters, the most successful candidate has now been identified. This was announced at a press conference on 9 July 2020 following publication of the research results on bioRxiv, an open access preprint server. While the study is yet to be peer reviewed, the researchers involved are very optimistic about the results: “The candidate vaccine offers good protection, works fast and one dose is enough.”
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KU Leuven’s COVID-19 vaccine development enters new phase
“The new vaccine is based on an existing yellow fever vaccine that has proven its effectiveness time and again,” explains Prof. Johan Neyts. “It has been in use for more than 80 years. During that time, almost 800 million people have been vaccinated with it. One dose of the vaccine results in lifelong protection against yellow fever.” Prompted by this track record, Rega Institute scientists decided to modify the existing yellow fever vaccine in hopes that the new variant could also provide protection against COVID-19. This modified vaccine was then tested on hamsters.
The hamsters were divided into different groups. One group was vaccinated, the other was not. In this way, the researchers tested eight candidate vaccines. “We wanted to investigate which of those eight candidates works best,” says Neyts. “Now that we have identified the most effective vaccine, we will further investigate it.”
The ‘winner’ turned out to work particularly well in hamsters: even after a single dose of the vaccine, the rodents developed a powerful immune response. “The vaccinated hamsters proved to be very well protected,” Neyts explains. “A single injection was enough to greatly reduce the number of virus particles present. In fact, four weeks after vaccination, there was virtually no trace of the virus left.”
The fact that one dose is sufficient could be important in the long run. “The more injections you need, the more vaccine you need to produce,” Neyts continues. “If you have to inject people two or three times, it’s also much more difficult logistically. Whether the vaccine also offers long-term protection is not yet clear. We won’t be able to tell that for a few months. But we’re hopeful, because we’re seeing a very powerful immune response.”
Furthermore, the hamsters’ immune systems didn’t go into overdrive after vaccination. That’s an important finding, because overactive immune systems are at the root of many complications currently observed in COVID-19 patients.
The candidate vaccine was named RegaVax, after the Rega Institute where it was developed. It will now be further investigated through animal tests. Afterwards, clinical research on human subjects will follow. “It’s still too early to start looking for test subjects,” comments Prof. Corinne Vandermeulen. “If all goes well, we can start clinical trials in December.”
The researchers emphasize that they have no commercial ambitions. “It’s not our intention to make a lot of money,” says Dr. Kai Dallmeier. “Our motivation is purely humanitarian. We are developing this vaccine for the people who need it. If we work with a pharmaceutical company in the future, we want guarantees. The vaccine must be made available at a fair price.”
Despite the long road ahead, the researchers are optimistic. “We have worked day and night over the past few months to get to this point,” Neyts concludes. “So far, everything has gone smoothly, but you never know for sure how everything will play out. Only around 10% of all vaccine candidates pass the final test. In other words, only a dozen of the 120 vaccines currently under development around the globe will ever be used. We are hopeful that our vaccine will be one of them.”