Booster vaccinations are needed because the number of antibodies in the blood decreases over time. For mRNA vaccines, this usually happens about six months after the first immunization against Covid-19. And for other vaccines, such as the single dose from Johnson & Johnson, the Standing Vaccination Commission in Germany recommends giving the booster dose even earlier.
But whether this will be the case in the future, asks Fabian Schmid in an analysis for Deutsche Welle, quoted by investor.bg. Should we have a booster vaccination every six months or every autumn, as in the future? Doctors still have no answer to this question; they need more experience. And different aspects have to be taken into account: For example, that new variants of the coronavirus will appear in the future, to which vaccines will have to be adapted – again as with the flu.
Is SARS-CoV-2 becoming endemic?
The development of the pandemic will definitely play a decisive role. It is not known whether the pandemic will die out after the fourth or fifth wave, or whether Covid-19 and its variants will become endemic, i.e. will appear regularly and for decades in certain regions.
The other important issue is that of group immunity. Will we make it soon? And will this be done through vaccination or through accidental mass infections, as is still the case in much of Africa? In the context of the current high number of new infections, something similar could happen in Europe.
The key role of T cells
When we talk about immunity, we need to consider not only antibodies, but T cells as well. A study by scientists from Great Britain and Singapore published in the journal Nature on November 10 provides more information on the subject. The researchers identified health workers at high risk of infection who had not been infected with Covid-19 or tested positive for PCR for months. Nothing abnormal was found in the serological antibody tests of these 58 employees.
However, it turned out that compared to another test group that was at a lower risk of infection, all of these 58 people developed more than the so-called. T cells – memory cells that are part of long-term immunity.
At the same time, larger amounts of IFI27 protein, which is an indicator of a very early SARS-CoV-2 infection, were found in the test subjects. From this, the researchers concluded that they all had mild or “abortive” infections.
In this case, it was likely the T cells that intervened and stopped the infection. However, it is not clear where the people examined got strong T cells: this may have been due to a previous infection with another coronavirus – such as a cold.
Will we achieve group immunity?
This would mean that sequential exposure to coronaviruses can help the immune system develop better defenses with both antibodies and T cells. This protection brings us closer to what is known as herd immunity.
However, experts warn that no one should feel invulnerable, as the risk of a lack of immunity remains high.
And the question of whether we need to be vaccinated again next autumn remains open.