In Germany, the biologist Wyler is working in a team with scientists from the Charité under the leadership of the FU Berlin on a nasal spray vaccine that, like the Codagenix vaccine, is based on weakened corona viruses. The advantage here is that a complete virus is presented to the immune system – and not just individual proteins as in most of the other corona vaccines currently available. It is hoped that this will provide better protection against newly emerging variants. Wyler considers it extremely unlikely that the vaccine virus itself will regain the ability to multiply massively and cause disease. “We changed 200 of the virus’ 30,000 building blocks to mitigate it – that’s a big hurdle.”
Results from animal experiments were therefore successful: the vaccine elicited an effective immune response in hamsters, after two doses the animals showed almost no signs of disease and very low levels of inflammation after a targeted infection with the coronavirus. As a booster after a previous mRNA vaccination, the nasal vaccine protected better than two mRNA vaccine doses alone. “In cooperation with the company Rocket Vax, the project is now moving towards a clinical study,” explains Wyler. “First of all, the tolerability of the preparation is to be proven in a phase 1 study on around 100 test persons and the dosage is to be checked.”
Important safety aspects
A safety issue specific to an intranasally administered vaccine relates to proximity to the facial nerves. A Swiss pharmaceutical company’s nasal flu vaccine was withdrawn from the market in 2001 after a rise in cases of facial paralysis among those who had been vaccinated. “This is a possible side effect of such products that we need to look at carefully,” says Wyler. At the moment, only one nasal mucosal vaccine is approved in Europe for children and adolescents against influenza.
But do we still need such vaccines in the corona pandemic? After all, in many countries the immunity of the population has increased significantly thanks to vaccinations and as a result of infections. Klaus Stöhr, epidemiologist and, among other things, a member of the Corona Expert Committee, which independently evaluated the federal government’s corona measures, is skeptical.
“Nasal vaccines have nothing to do with the outcome of the pandemic and if they were approved in industrialized countries in a few years’ time, they would have no significant impact on the emergence of escape variants or virus circulation,” Stöhr recently wrote on Twitter. According to Stöhr, approval in all age groups is “extremely unlikely” – but widespread use is necessary to stop the virus circulation or to prevent the development of immune escape variants.