Vaccination strategy against Corona – preparation for new virus variants

Vaccination card with vaccination syringe, negative rapid corona test and vaccine vials from Biontech and Moderna (imago images / Christian Ohde)

Corona vaccinations do not reliably protect against infection with the omicron variant. But they ensure a basic immunity that protects those infected from a severe course of Covid-19, says Leif-Erik Sander, vaccine researcher from the Berlin Charité and member of the Federal Government’s Expert Council:

“That is my belief that if we have three shots we have very good immunity. The protection of the mucous membrane decreases over time, and then of course the antibody titers in the blood decrease again, so that we can become infected. But we can see that the burden of disease is massively reduced in those who have been boosted. And I believe that we will then boost ourselves through repeated natural antigen contact with circulating viruses. And I think that will happen to large parts of the population.”

Infection also boosts the immune system

Basic immunization via vaccinations plus occasional infection with the virus – this is what living with the new type of corona virus will probably look like in the future, according to the expert. At least for the majority of the population. At the same time, it makes sense to give additional protection to people with an increased risk of a severe course of Covid. With vaccines adapted to new variants of the virus. Such preparations will soon be available, said Klaus Cichutek, President of the Paul Ehrlich Institute on Friday at an event hosted by the Science Media Center Germany.

Variant-adapted vaccines could be approved quickly

“I think it’s important to realize that we’ve set the course here so that a quick switch to new variant vaccines and thus also Omicron-adapted vaccines is actually possible. And the fact is that both Biontech/Pfizer, Moderna and Janssen have already switched certain parts of the production of the vaccines in order to start clinical trials. These will then start in the next few weeks, so that we can assume in the second quarter of this year that the relevant data will be available to be able to approve the vaccines. Or rather, there will then be simple variations on the original approval in order to become technical.”

Universal vaccines are under development

In the long term, however, it could also make sense to develop multivalent, i.e. universal vaccines that target different variants of the coronavirus. These can attach to different regions of the virus, the so-called epitopes. Current vaccines enable the immune system to recognize special structures of the so-called spike protein of the virus, with which the pathogen penetrates the cells. Leif-Erik Sander from the Charité thinks it is promising to develop multivalent vaccines that respond to mutated variants of the spike protein. This is because a broader immune response could be achieved in this way.

“And of course we will then understand even better which epitopes might be addressed by responses that are less easy to neutralize in the virus. These are also principles that are being followed in the development of universal influenza vaccines. And that’s why I personally find this approach with multivalent spike vaccines the most attractive at the moment, because we have very, very good evidence that spike-targeted vaccines work extremely well, that they can probably also be adapted.”

Sterile immunity remains a pipe dream

According to Sander, such a universal corona vaccination could be given to all people as basic immunization in the future. Possibly in combination with a flu vaccine. However, it is still unclear when and how often vaccinations against the novel corona virus should be administered in the future. Experts assume that this immunization does not protect people from mild infections with the pathogen. But it probably prevents those infected from becoming so seriously ill that they have to go to the hospital.

At the same time, researchers are working on administering corona vaccinations via the mucous membranes. For example as a nasal spray. The hope behind this: If the immune system produces enough antibodies locally in the mucous membranes, these could already prevent an infection and thus bring about so-called sterile immunity, explains Klaus Chichutek, President of the Paul Ehrlich Institute:

“That’s a good approach, there are initial clinical trials on it. There will also be an approach from the German Center for Infection Research. You can try that. However, I don’t think there is much hope for sterile immunity in the case of a respiratory infection. Even with such nasally applied vaccines, we also find that from the influenza area.

A second booster vaccination is apparently of little use in the current pandemic. This is indicated by data from Israel. It remains to be seen whether further booster vaccinations make sense a few months apart.

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