The development of a vaccine against the coronavirus is to be accelerated with the help of carriers – scientifically speaking vaccine vectors – explains virologist Christian Drosten in the NDR podcast. One has already had good experiences with vaccine carriers and live vaccines. Proteins and antigens from the corona virus can be built into such a system.
The vaccine can then be administered to humans and an immune response takes place. However, the preclinical phase is very important with this model, according to Drosten – the period before a person is even treated with the vaccine. Long-term validated data were already available for certain carriers, which, for example, confirmed the tolerance of the vaccine carrier. This could shorten the development of a vaccine somewhat.
Findings from very similar virus strains
However, it is now difficult to simply administer the vaccine to healthy volunteers and then infect them with the virus in the laboratory. The infection under controlled conditions and in the wild would differ significantly, according to the virologist.
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One approach is therefore to understand the natural infection and natural immunity and to reproduce them as best as possible. “But that’s an approach that we may not have time for at the moment,” said Drosten. Another approach is to use experience with very similar infections – in this case the SARS virus – to clarify questions about the potential vaccine.
Vaccine research with existing antigens
Research on very strong, natural and already existing antigens would also be possible. These could recognize the surface structure of the corona virus at one of its most critical points, namely when the virus wants to penetrate the cell.
At this point, the virus would be rendered harmless. Another method would be to provoke a special active cellular immunity, according to Drosten. Here, immune cells are “woken up” by a vector carrier, which then elicited a strong immune response and eliminated the virus.
Dead vaccines may be less suitable for coronavirus
In addition to live vaccines, dead vaccines are also known – and are already under discussion. Attenuated viruses or bacteria are administered. This type of vaccination has disadvantages – on the one hand, incomplete immunization can occur, since only part of the immune cells are stimulated. On the other hand, special “killer cells” of the immune system that actually eat up the harmful virus can become the host themselves by ingesting the virus – and the virus multiplying in them.
The corona virus can thus weaken or even kill the “killer cell”, resulting in a disturbed immune response. A vaccine that produces the wrong or too few of the required antibodies, Drosten says, could thus provoke a worse course of the disease Covid-19. However, the “antibody-dependent aggravation”, as it translates to the Virsequ, is a primarily theoretical model.
Those effects should absolutely be excluded, according to the virologist – through tests in a test tube, but also through animal experiments. It is difficult to say whether cellular immunity or antibody immunity is better, said Drosten.
“There are very promising starting dates for both approaches.” A company that undertakes this giant project in vaccine development will have to decide on one or the other option at some point.