The second corona booster is already recommended for older people. Experts disagree on expanding to other groups. Is the first refresher enough?
In the debate about an extension of the recommendation for corona fourth vaccinations, experts continue to be very skeptical.
Protection against severe gradients
Wanting to achieve complete protection against infection by repeated boosters is probably not a realistic goal, said Christoph Neumann-Haefelin, head of the Translational Virus Immunology working group at the University Hospital Freiburg. “The aim of the booster vaccination must be to protect the various groups of people from really serious infection progressions.”
In healthy people without immune problems, a relatively robust T-cell response lasts for almost a year after the second vaccine dose, Neumann-Haefelin explained. The first booster vaccination temporarily increases the protection again, also through increased levels of antibodies, and contributes to its duration.
So-called neutralizing antibodies can – if there are enough – already prevent an infection, they are the first line of defense in the body. T cells, on the other hand, are important for protection against severe courses. After corona vaccinations, the levels of neutralizing antibodies in the blood, which initially increased, drop again very quickly. Significantly higher levels are required to protect against infection with the Omicron variant, which appeared at the end of 2021, than with earlier variants – this is one of the reasons why the booster campaign in Germany was expanded.
Vaccination “extremely efficient”
The drop in antibody levels after an infection or vaccination is “a completely normal process,” said the scientific director of the German Rheumatism Research Center Berlin, Andreas Radbruch. What is often neglected in the discussion: There is then less mass, but the quality of the antibodies increases – “and quite drastically”. This very important process (affinity maturation) lasts about half a year and cannot be shortened: If you are now considering a second booster, you can “wait until autumn” against this background. All in all, Radbruch described the vaccination as “extremely efficient”, and long-lasting protection can be assumed.
Christine Falk, President of the German Society for Immunology, said about fears of possible future virus variants that undermine the vaccination protection that the spike protein of Sars-CoV-2 has remained very constant in its lower range since Wuhan. Further changes to the extent that these areas are no longer recognizable for T cells she described as very unlikely.
In general, the immune responses of people to the vaccination could be very different from person to person, Falk said. From a purely immunological perspective, one could say that people under the age of 70 with a healthy immune system produce a very good, sustained, protective immune response against a severe course. “That is also the claim that we had for the vaccination.”
Recommendation of the vaccination commission
The scientists emphasized that there is still no consensus about the values, for example of antibodies in the blood, at which a person is protected from a corona infection. Antibody levels in the blood also said nothing about the protection in the nasopharynx.
In Germany, the Standing Vaccination Commission currently only recommends a second booster for people over 70 and people with certain previous illnesses. Federal Health Minister Karl Lauterbach (SPD) recently campaigned in Brussels for a fourth vaccination for everyone over 60 years of age. At the beginning of April, the EU medicines agency EMA declared that a fourth dose is currently not necessary for all citizens: However, it could make sense for people over 80 years of age given the higher risk of severe Covid disease.