Regardless of the recommendation of the Standing Vaccination Committee STIKO, many people are currently wondering whether they should be vaccinated – even if they may not belong to the risk group. With antibody tests there is the possibility to check the immune status with a blood test. The physician and director of the Institute for Laboratory Medicine at the University Hospital in Giessen and Marburg, Harald Renz, explains who a blood test could be worthwhile for.
Mr. Renz, many people are uncertain at the moment. Actually they are double vaccinated and boosted, some even went through an infection. But now the adapted bivalent vaccines are coming to the doctor’s office. Can you test whether you should have the fourth vaccination, i.e. the second booster, or whether you can do without it?
Before I answer the question, let’s take a look at who is protected and how well. The best protection right now is if you have hybrid immunity. Vaccinated twice and infected once naturally, that is the best we can achieve.
Because then you didn’t just come into contact with the vaccine antigen and the immune system didn’t just get to know the prickly spike protein?
Exactly. Many more B-cell and T-cell viral epitopes are recognized in the immune response after infection. The innate and adaptive infection response is therefore broader than if you were only vaccinated three times. The hospitalization rate and mortality is the lowest with this type of immunization after an infection.
Laboratory physician Harald Renz
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Image: HR Kittel
There are still many people who have been able to avoid the real virus so far…
Among these, the hybrid vaccinated or hybrid boosted are the best protected – i.e. those who had a mix of the different vaccines.
The intervals between vaccinations or between vaccination and infection is emphasized as an important factor in building immune memory. How big should the distance be?
Four to six months is ideal. It takes time for the immune memory to build up sufficiently. If the body’s defenses are activated too quickly, the antibody concentrations shoot up very quickly, but the infection is effectively combated as a result. But the immune system doesn’t have enough time to build up B and T cell memory. The goal of vaccination, long-term protection against disease and death, is not achieved. Because of all the activation, the immune system becomes exhausted.
If the interval is right – so the first booster was six months ago – should you be vaccinated again with the new, adapted vaccines?
The second booster makes sense for people with a risk constellation (age, underlying disease). This is not absolutely necessary for healthy younger people. The second booster with the adapted vaccines provides good protection against severe courses and may also reduce the risk of long-Covid. But it is important to say that a second booster, according to everything that is known, does no harm.
Can you overboost?
If you keep the vaccination intervals, there is no risk of this.
That doesn’t make the decision any easier. Can I get tested to see if I have good protection?
Yes, that’s no longer a problem. Antibodies against the S and N proteins can be detected in a routine blood count, which any general practitioner can commission from the laboratory. If you have a lot of S antibodies, you are well protected by the vaccination. If you have a lot of N-antibodies, this indicates protection from the infection. When vaccinated, antibodies are only formed against the spike protein, i.e. against “S”.
A year ago, such self-payer antibody tests cost around 100 euros…
At least that is no longer the case today. The detection is semi-automated or even fully automated in the laboratories, it is an absolute standard. However, many general practitioners do not know that they can simply commission these tests.
For whom is such a test useful?
Such a test can be used to identify low responders who hardly develop any immune protection after vaccination or infection. With them, the doctors should then think about a changed vaccination schedule – about hybrid vaccinations. The group of low responders is relatively large, including many patients with chronic diseases such as obesity, diabetes and cardiovascular diseases. Your immune system is not responding well enough either because of your illness or because of the medication you are taking.
