The yellow fever vaccine, which is already around 80 years old, also works against COVID-19. Virologists at the Rega Institute at Belgian University KU Leuven have recorded good results with this vaccine in tests on hamsters. Belgian researchers will begin their first clinical trials in humans later this year. The study was published on bioRxiv’s pre-print server awaiting peer review.

A team led by Prof. Johan Nates and Dr. Kai Dallmeier began in January the development of eight vaccine options for the new coronavirus. In the course of the tests, one vaccine was revealed, which, apparently, works especially well in hamsters. After the introduction of this vaccine, the virus was no longer or was barely detectable in experimental animals.

In hamsters that received the candidate vaccine, scientists observed up to half a million times less viral infection than in hamsters from the control groups. Moreover, even a single dose of the candidate vaccine was enough to protect against infection.

The candidate vaccine was made on the basis of the existing yellow fever vaccine and, thus, is capable of eliciting an immune response with both COVID-19 and yellow fever in experimental animals. Part of the genetic code of the SARS-CoV-2 virus was included in the yellow fever vaccine. The team has already used this platform to create candidate vaccines against Ebola, Zika, and rabies.

Yellow fever vaccine has proven effective more than once, scientists say. It has been used for about eighty years, and 800 million people have been vaccinated over this period. A single dose of the vaccine provides lifelong protection against yellow fever. Of the more than 160 vaccines being developed to control COVID-19, KU Leuven’s virologists are the only ones using yellow fever as the basis.

To select the most effective of the eight vaccine prototypes, they not only checked which prototype generates the most antibodies in hamsters, but which one provides the most effective protection against infection. This increases the chances of scientists to find the most successful candidate for the role of a rescue vaccine.

A candidate vaccine stimulates the body to produce antibodies against coronavirus, thereby preventing the virus from adhering to healthy cells. Scientists conclude that the yellow fever vaccine also works against COVID-19.

Given that an experimental vaccine from a research laboratory cannot simply be administered to people, a specialized company accredited for this purpose should now produce a candidate vaccine. The team is currently in talks with manufacturing partners.

Scientists hope that the first human clinical trials will begin by winter.