Anyone who has survived a corona infection is considered to have recovered. A natural immune protection was built up. However, vaccination is recommended for them too. Why actually?
People who can be shown to have survived a corona infection can describe themselves as recovered and enjoy a similar status in the pandemic to those who have been vaccinated twice. But only for a certain time. Because if the infection was more than six months ago, it is officially no longer considered protected. An additional vaccination is recommended. But why, when and, above all, how often should convalescents be vaccinated?
Why do those who have recovered need to be vaccinated at all?
Immediately after surviving a corona infection, people are usually well prepared against the virus. If there is a new contact with the virus in this phase, it runs, figuratively speaking, against a bulwark of antibodies and T cells. The immune system identifies the unwanted intruder and repels it.
But: the body’s own virus interception system does not last forever. How long the protection lasts after recovery is different for each person and depends on the respective immune response. For example, some people make a lot of antibodies, while others develop very few. Various factors such as age or an immune system that has been suppressed by drugs are involved. In addition, the antibody level drops over time – with some faster, with others more slowly. According to the current state of knowledge, the protection lasts for at least a few months. Vaccination is therefore recommended as a booster.
What is Hybrid Immunity?
People who are infected with a certain corona variant also develop antibodies specifically against these. This can become problematic if you come into contact with other variants such as the currently rampant Delta variant. The vaccination could increase protection against other variants such as the now predominant delta variant.
The US virologist Shane Crotty told the AP news agency that those who have recovered after vaccination can produce antibodies that are effective against all corona variants. He calls this “hybrid immunity”. The head of the Standing Vaccination Commission (Stiko) Thomas Mertens also told the “Spiegel” that there were “very good data” from England, based on which one can see “that the protective effect after an alpha infection and after a complete vaccination also with the Delta variant is good “.
Vaccinate once?
Stiko recommends that people who have already had a corona infection be boosted with a vaccine dose. The vaccination should ensure that the immune system gets another boost. “Good data show that vaccination can also have a very good booster effect in people who have had an infection,” quotes “Spiegel” Mertens. Since the vaccination builds on the already existing immune protection, it is possible that the antibody levels after the vaccination are even higher than after two vaccinations.
This is also confirmed by a study carried out by researchers at Rush University in Chicago. They also observed that those who recovered from a vaccination produced more immune cells that worked against the virus than people who were not infected but were vaccinated twice.
Vaccinate twice?
“Due to the existing immunity after previous infection, one dose is sufficient,” states the Stiko in its recommendation for vaccinating those who have recovered. This made it possible to achieve high antibody concentrations that would not be increased by a second dose of vaccine. Even if more than six months have passed since the diagnosis, one dose of vaccine is sufficient for a complete basic immunization. Immunologist Carsten Watzl agrees. He not only thinks a second vaccination for those who have recovered is unnecessary, he already described it as a waste at the beginning of June. They no longer change the antibody level noticeably
However, a study from Great Britain that was published in “Science Translational” stands in the way of this. According to this, a second dose with an mRNA vaccine did indeed lead to an increase in the number of neutralizing antibodies and thus the protective effect against the corona variants beta and gamma was strengthened. The effect on Delta has not been studied.
It is a very small study involving 45 hospital employees. 20 of them were infected before the first vaccination. All participants were vaccinated twice with the Biontech / Pfizer vaccine. It was found that the antibody response to beta and gamma was significantly increased by the second dose. The researchers assume that for broad antibody protection, both vaccinations are also necessary for those who have recovered. The restriction: It is a laboratory analysis. In addition, the researchers only looked at the antibody response; T cells were not included in the study.
Whether and when a second corona vaccination will be necessary at a later point in time, writes the Robert Koch Institute (RKI), cannot currently be said. In the case of people with impaired immune function, it should be decided on a case-by-case basis whether one vaccine dose is sufficient or a complete series of vaccinations should be administered. This depends largely on the type and degree of immunodeficiency.
Don’t vaccinate?
Anyone who has recovered is usually immune to a severe corona infection for at least a few months. But according to current knowledge, the protection does not last forever, but rather diminishes over time. If you want to arm yourself against the virus, you have to get vaccinated. According to the RKI, there are no indications in the study results available so far that “vaccination after a previous SARS-CoV-2 infection would be problematic or associated with risks; this applies to the safety, effectiveness and tolerability of the vaccination.”
When to vaccinate
Until recently, those who had recovered could pick up the vaccination six months after the infection, but now this is possible as early as four weeks after the symptoms have subsided. According to Stiko, all approved corona vaccines can be used as a booster vaccination.
However, the Vice President of the German Society for Immunology told the “Berliner Zeitung”: “You can see that a second vaccination with an mRNA vaccine gives a much better immune boost to people who have already been vaccinated than a second vaccination with a vector vaccine assume that mRNA vaccines have a stronger protective effect on people who have recovered than vector vaccines. “
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