Covid-19: Hope for a passive vaccination

Christiane Fux studied journalism and psychology in Hamburg. The experienced medical editor has been writing magazine articles, news and factual texts on all conceivable health topics since 2001. In addition to her work for, Christiane Fux is also active in prose. Her first crime novel was published in 2012, and she also writes, designs and publishes her own crime plays.

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Passive vaccinations are used to treat various diseases. They contain antibodies that render the pathogens harmless in the body of an infected person. Such a vaccination could also protect SARS-CoV-2 infected people from severe disease - or help seriously ill people to recover.

In addition, it could arm healthy people who have had contact with infected people in advance against the virus - but only for a certain time.

Researchers from the Berlin Charité and the German Center for Neurodegenerative Diseases (DZNE) have found an important basis for the development of a passive vaccination against COVID-19: They have identified highly effective antibodies against the coronavirus SARS-CoV-2.

Plasma donations with antibodies are already being used

Plasma donations from recovered Covid-19 patients are based on the same operating principle as passive immunization and are already used to treat seriously ill infected people: The donated blood plasma contains specific antibodies against SARS-CoV-2, which the plasma donor's body against the virus during infection has formed. They can support the immune system of the seriously ill in the fight against the viruses.

But the effort involved in obtaining blood plasma and preparing it for a donation is high. In addition, the composition of the antibodies varies from patient to patient - and their effectiveness varies. In addition, the administration of blood plasma can cause side effects.

Making the most potent antibodies in bulk

The aim of the research team led by Dr. Jakob Kreye and Dr. Momsen Reincke is therefore developing drugs that contain pharmaceutically manufactured antibodies against SARS-CoV-2. “Ideally, the most effective antibody is produced in a targeted manner on an industrial scale and with consistent quality. That is the goal we are pursuing, ”says Reinecke.

To identify the most effective antibody candidates, the scientists first isolated almost 600 different antibodies from the blood of recovered Covid 19 patients.

Antibodies block the virus

Through laboratory tests, they were able to narrow this number down to a few particularly effective specimens. They then had them artificially recreated using cell cultures.

The selected so-called neutralizing antibodies couple to SARS-CoV-2 and thus prevent the pathogen from penetrating into body cells and multiplying. In addition, viruses marked with antibodies are eliminated more quickly by immune cells.

Proof of effectiveness in hamsters

Studies on hamsters, which, like humans, are susceptible to infection by SARS-CoV-2, confirm the high effectiveness of the selected antibodies. “If the antibodies were administered after an infection, the hamsters developed mild symptoms at best. If the antibodies were given preventively - before infection - the animals would not become ill, ”says Kreye, who coordinates the research project.

How long does the vaccination work preventively?

How long the preventive protection of such a passive immunization exists must be investigated in the context of clinical studies: "In contrast to active vaccination, finished antibodies are administered with passive vaccination, which are broken down after a certain period of time," explains Prof. Harald Prüß, Research group leader at the DZNE.

As a rule, protection from passive vaccination is therefore less permanent than from active vaccination. In return, the effect of a passive vaccination is almost immediately available. In the case of an active vaccination, this must first build up. "It would be ideal if there were both vaccination options so that we can react flexibly to the situation."

Clinical studies in humans are still lacking

Clinical studies have yet to confirm the effectiveness of passive vaccination in human subjects - and also its tolerability. Some SARS-CoV-2 antibodies not only bind to the virus, but also to various organs, which could trigger undesirable side effects. The researchers expect that approval could take place at the end of this year at the earliest.

They are already working together with a partner from industry to create the prerequisites for effectively producing the antibodies in large quantities. Then production could be ramped up quickly after approval.

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