Pretty much every German has probably come into contact with the coronavirus by now. Be it through an infection or through vaccination. The immunity we have achieved has now even prompted the Standing Vaccination Commission to issue a new vaccination recommendation: boosters will only be necessary for risk groups in the future.
So we are immune. But how long will we stay this way? A new study from South Korea provides insight into this.
Scientists are studying corona immunity
Scientists from Korea Virus Research Institute Center for Viral Immunology had examined blood samples from various people including
28 who received three doses of the mRNA vaccine from Pfizer/Biontech 22 who suffered an infection with the original Wuhan-Hu-1 virus strain and two doses of the mRNA vaccine and 68 who received three doses of the mRNA vaccine and subsequently a breakthrough infection
had suffered.
The team found:
For all groups, the mRNA vaccines generated so-called helper and killer cells, parts of the immune response that attacked the spike protein of the omicron subvariants BA.4 and BA.5. And that even applied to those who were infected with the original Corona strain.
The coronavirus uses this spike protein to infect human cells. It is located on its outer shell and binds specifically to the ACE2 receptor on the surface of human cells. This allows the virus to fuse with the human cell membrane and transport its genetic material into the interior of the cell, where it continues to multiply. For this reason, the spike protein is a target for corona therapies and vaccinations. However, if it has mutations, this increases the risk that it will bypass immunity from previous infections and vaccinations – and that is exactly what makes the coronavirus and its mutations so treacherous.
The researchers made another discovery:
Certain formed cells, the so-called CD8+ T cells, which were triggered by a breakthrough infection with the omicron variant BA.2, did not only react with the BA.4/5 spike protein. They also did this with the currently circulating corona variants, such as the XBB lines. So that means: The body built up a broad immune memory. So he comes up against the treacherous mutations.
Immune system is not subject to “antigenic sin”
The cells that the body develops are not subject to the so-called “antigenic sin,” says immunologist Carsten Watzl, classifying the study results. “That is new.”
This “antigenic sin” refers to the process in which, after a first contact with a virus, the immune system only produces antibodies against the first virus variant upon further contact with a similar virus variant.
“The study shows that with regard to T cell responses, every additional infection with variants increases the breadth of the immune response to Sars-CoV-2, so that future variants are also increasingly better covered,” explains the Secretary General of the German Society for Immunology continued: “The same will probably happen with vaccination with variant-adapted vaccines, although these have not been examined here.”
Study leader Min Kyung Jung says: “This finding opens up new perspectives for us in the new era of the endemic Covid-19 crisis.” He adds: “It is understandable that our bodies have also adapted in response to the constant emergence of new virus variants to combat future strains of the virus.” The results were published in the journal “Science Immunology”.
“It can be assumed that, based on the widespread infection of the population, supplemented by the vaccinations, there is a broad T-cell immunity that protects against severe disease progression,” adds Juliane Walz, the medical director of the Translational Immunology Clinical Cooperation Unit at the University Tübingen University Hospital. However, booster vaccinations remain important for risk groups.
Anyone who still needs booster vaccinations
Stiko recommends the following people:
People over the age of 60, residents in care facilities and people with an increased risk of a serious illness in integration assistance facilities. People aged six months and over with an underlying illness that is associated with an increased risk of a severe course of Covid-19 People of all ages with an increased work-related risk of infection in medical and/or nursing care with direct contact with patients or residents. Family members and close contacts from the age of six months of people who do not have a protective immune response after a Covid-19 vaccination is to be expected.