The vaccine is considered a great hope in the fight against the corona pandemic. However, the spreading mutated Sars-CoV-2 variants are causing increasing concern. Variant B.1.1.7, which first appeared in Great Britain shortly before Christmas, has now been proven in Germany. Mutations that have now also appeared in Germany are also curing in South Africa and Brazil. The big question is: Are these gene variants possibly able to undermine the immune defense after a disease or even after a vaccination?
Mutations in viruses are not unusual. At first it also looked like they couldn’t harm the vaccine. After all: for the second time, Pfizer and Biontech provided evidence on Wednesday that their vaccine is at least effective against the variant discovered in Great Britain. The crucial parts of the so-called spike protein do not appear to be changed so much that the immune response that the vaccine elicits is weakened.
As the “Ärzteblatt” writes, immunlogists are currently divided on how great the risk is, whether and to what extent the new variants of Sars-Cov-2 evade antibody protection. The specialist portal refers to two studies.
Gene variant from South Africa: In 48 percent of the test persons, antibodies could not stop the virus
Just like the variant that occurred in Great Britain, the mutants that were first discovered in Brazil, South Africa and most recently in California also have mutations in the receptor binding sites of the spike protein, writes the “Ärzteblatt”. Antibodies that the body produces after an illness or vaccination could lose their protective function. Because the strongest of them start precisely at this receptor binding point.
This does not necessarily have to mean that the vaccines no longer work or that patients who have already survived Covid-19 are no longer protected. However, there is a risk, writes the “Ärzteblatt”.
In a study published on the BioRix preprint server, researchers came to the conclusion that the South African variant was in some cases no longer recognized by the antibodies in the blood of patients who had already survived the disease. The result: a decrease in the neutralizing effect. In 48 percent of the test persons, the antibodies were no longer able to prevent the virus from multiplying, write the researchers working with Penny Moore from the University of Witwatersrand in Johannesburg.
The effect was only satisfactory in three patients who had previously survived a severe course of the disease. The results of the study therefore give rise to concerns that people who have contracted a disease with other variants are not protected against reinfection with the mutant.
Weakened effect of antibodies in the event of mutations
In contrast, a team led by Michel Nussenzweig at Rockefeller University in New York has examined how the new gene variants affect the protection provided by the vaccines from Moderna and Biontech. As expected, the vaccinated had developed high antibodies against the spike protein eight weeks after the second dose – and thus a good protective effect against the currently circulating “normal” variant.
However, if the serum was prepared for viruses of the South African or British variant, the protection was reduced according to the “Ärzteblatt” in the laboratory experiment. 14 of the 17 strongest antibodies that attack the receptor binding site were affected. Although these results sound quite devastating, Nussenzweig comes up with a relatively favorable verdict. The researcher writes that the neutralizing effect is only slightly weakened. Antibodies attacking the spike protein elsewhere could maintain the protection of the vaccine.
It is also important to know: Antibodies are only one of the important factors for immune protection. Another is what is known as T cell immunity, which is controlled by the T cells. Charité virologist Christian Drosten recently said that this would protect much more against severe courses. So he doesn’t think we should expect vaccines to fail.