Rega Institute, KU Leuven come up with vaccine candidate against COVID and Yellow fever

Virologists at the Rega Institute at KU Leuven (Belgium) have developed a vaccine candidate against COVID-19 supported the yellow jack vaccine, which as a result also works against yellow jack .

Results published today in Nature show that the vaccine protects hamsters from infection with the SARS-CoV-2 coronavirus after one dose. The vaccine is additionally effective in monkeys. The team is currently preparing for clinical trials.

To engineer their vaccine, tentatively named RegaVax, the team led by Professor Johan Neyts and Kai Dallmeier inserted the ordering of the SARS-CoV-2 spikes into the ordering of the yellow jack vaccine. The researchers tested the vaccine in healthy hamsters and monkeys. Another group of the animals received a placebo.

The researchers first vaccinated the hamsters then dripped the virus into their noses. Ten days after one vaccine dose, most of the hamsters were protected against the virus. Three weeks after vaccination, all hamsters were protected. “They also didn’t develop any lung infections. The lungs of the hamsters within the control groups, against this , showed clear signs of infection and disease,” Neyts explains.

The team also tested the vaccine in monkeys. “In a number of the monkeys, we observed neutralising antibodies already seven days after vaccination. After fourteen days, high titers of neutralizing antibodies were measured altogether animals. this is often in no time . Moreover, within the vaccinated animals, the virus was completely or nearly completely gone from their throats.”


“Ours is that the only vaccine currently in development against Covid-19 that also protects against yellow jack ,” explains professor Neyts. Previously, the Rega team used the yellow jack vaccine because the foundation for vaccine candidates against Zika, Ebola, and rabies. “The effectiveness and safety of the yellow jack vaccine, which has been in use for 80 years, is well-established. quite 500 million people have already received this vaccine. One dose offers fast protection against yellow jack that in nearly all cases lasts for all times .”

“A vaccine that works against COVID-19 and yellow jack could offer a crucial contribution to the WHO’s campaign to eradicate yellow jack by 2026,” Neyts continues. “Especially now that we all know there are mosquito species present in Asia which will transmit the yellow jack virus.”

RegaVax works after one dose, unlike many of the front-runners within the race today, which require a repeat vaccination after one month. “This has important logistical implications, especially for countries with a less advanced medical system,” explains professor Neyts. “Additionally, we expect that the vaccine will offer long-lasting immunity to COVID-19. It could therefore be a perfect candidate for repeat vaccinations when immunity decreases in people that have received one among the first-generation vaccines.”

Finally, the vaccine are often stored at 2-8 °C, while some vaccines require a chilly chain with temperatures right down to -70 °C. That’s already challenging within the Western world, but it’s going to be nearly impossible to vaccinate large populations in remote tropical and subtropical regions,” Neyts explains.

“An inexpensive, single-dose vaccine that rapidly protects against infection, which will be stored and transported at fridge temperature, which may, just like the yellow jack vaccine on which it’s based, end in long-lasting immunity, provides a crucial and much-needed diversification of the Covid-19 vaccine landscape,” Neyts concludes.

His team is now preparing for clinical trials next year and has joined forces with a specialised and accredited company which will produce the vaccine candidate for testing in humans.

New technique

RegaVax may be a vector vaccine: it uses the ordering of the yellow jack vaccine virus as a carrier (or vector) for the ordering of the coronavirus spikes. “When working with a related virus, like the Zika virus, pieces of the ordering of the yellow jack vaccine virus are swapped with an identical piece of the code of the targeted virus. Using this strategy the team recently developed a Zika vaccine candidate. However, since SARS-CoV-2 is unrelated to yellow jack , a replacement technology had to be developed to insert a completely unrelated genetic sequence within the yellow jack vaccine backbone. This concerns a crucial innovation within the vaccine field.”

Virus inhibitors

“Mind you: vaccines aren’t an answer for people that are already ill. that’s why we also are developing a cure to assist Covid-19 patients,” Neyts concludes. “We recently published on the protective activity of the japanese flu drug favipiravir in hamsters. we’ve identified another existing medicines or combinations thereof that inhibit the virus. We are now first exploring their effect in infected hamsters. At an equivalent time, we aim to develop new and powerful virus inhibitors against SARS-CoV-2. For this purpose, we’ve already tested quite 1.6 million molecules in our fully automated high biosafety laboratory. We’re trying to find a needle during a haystack.”

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