KU Leuven vaccine candidate protects against COVID-19 and yellow fever

Virologists at the Rega Institute at KU Leuven (Belgium) have developed a vaccine candidate against COVID-19 based on the yellow fever vaccine, which as a result also works against yellow fever. Results published today in Nature show that the vaccine protects hamsters from infection with the SARS-CoV-2 coronavirus after a single dose. The vaccine is also 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 genetic code of the SARS-CoV-2 spikes into the genetic code of the yellow fever 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 and then dripped the virus into their noses. Ten days after a single 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 in the control groups, by contrast, showed clear signs of infection and disease," Neyts explains.

The team also tested the vaccine in monkeys. "In some of the monkeys, we observed neutralising antibodies already seven days after vaccination. After fourteen days, high titers of neutralizing antibodies were measured in all animals. This is very fast. Moreover, in the vaccinated animals, the virus was completely or nearly completely gone from their throats."