What we can learn from Polio

Using weakened coronavirus strains for vaccine

The wide diversity of coronavirus symptoms make it likely that some variants of the virus are weaker than others. The trick is to find these strains and use them to develop a vaccine. An international group of scientists from 11 countries argues in favour of this approach, which proved to be successful in the historic fight against polio.  Prof. Ineke Braakman and Dr. Peter van der Sluijs from Utrecht University  joined the Dutch researcher Dr. Eelco van Anken working on the project in Milan.

The scientists believe that not enough attention has been paid to the possible attenuated strains of the coronavirus. These weaker versions may be the ideal raw material for large-scale use in vaccination. The currently limited degree of group immunity around the world makes this approach vital to save lives and to help restore the economy. This method of developing a vaccine may be faster than designing one artificially, and it is less expensive, which would facilitate the global application of the vaccine and help control the pandemic.

The natural evolution of the virus can help scientists follow in the footsteps of the fight against polio. The history of viruses has shown that those that are moderately strong have the greatest chance of survival, as viruses do not benefit from the death of their host. The weakest strains eventually die out because they lose the struggle to attack the cell, and therefore cannot be spread by the host. As a result, viruses naturally mutate towards a strain with less severe symptoms.

Linking virus genetic material to symptoms

Where the discovery of a weakened polio virus was a fortunate accident, current technologies make it possible to deliberately search for an attenuated strain. As far as the scientists know, only part of the pathogen’s genetic material has been examined so far, and those genes have not been linked to the patients’ pathologies. They therefore recommend identifying the genome of the virus variants in patients who show only mild symptoms. The weaker viruses found in this way can then be attenuated further (if necessary) and used for the production of vaccines.

Research into suitable milder variants should mainly focus on infections among risk groups. If the patients have managed to survive the infection without major problems, and if the divergent signature of the virus can be identified, then the next step towards a possible vaccine is simply one of technology and careful testing. The virus can then provide its own vaccine, as was the case with polio. Deliberately infecting people with a mild variant stops the advance of the harmful virus strains by means of a ‘scorched earth’ strategy and helps to build group immunity. The limited risks of working with an attenuated virus will require careful monitoring, however, as is currently the case with the vaccines for mumps, measles and rubella.



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Website: The SANE Project