Booster immunizations are needed because the number of antibodies in the blood decreases over time. In mRNA vaccines, this usually occurs about six months after the first immunization against Covid-19. And for other vaccines, such as Johnson & Johnson’s single dose, the Standing Immunization Commission in Germany recommends that the booster dose be given even earlier.
But whether it will be the same from now on, Fabian Schmid asks in an analysis for Deutsche Welle, quoted by investor.bg. Should we get a booster vaccine every six months or every fall, as in the future? Physicians do not yet have an answer to this question, as they need more experience. And different aspects need 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.
Will SARS-CoV-2 become endemic?
The development of the pandemic will definitely play a decisive role. It is not known whether after the fourth or after the fifth wave the pandemic will die, or whether Covid-19 with its variants will become endemic, ie. will appear regularly in certain regions, and for decades.
The other important issue is that of group immunity. Will we be able to achieve it soon? And will this be done through vaccination or through unintentional mass infection, as is still the case in large parts of Africa? In the context of the current high levels of new infections, something similar could happen in Europe.
The key role of T cells
When we talk about immunity, we must consider not only antibodies but also T cells. More information on the subject is given by a study by scientists from Great Britain and Singapore, which was published on November 10 in the specialized journal Nature. The researchers identified health care workers at high risk of infection who had not contracted Covid-19 for months or tested positive for PCR. Nothing distinctive was found in the serological tests for antibodies of these 58 employees.
But it turned out that compared to another test group, exposed to a lower risk of infection, all these 58 people have 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, considered an indicator of very early SARS-CoV-2 infection, were found in the subjects. From there, the researchers concluded that they all had a mild or “abortive” infection behind them.
Probably in this case it was the T cells that intervened and stopped the infection. But it is not clear where the people studied got strong T cells: it is possible that this was due to a previous infection with another coronavirus – such as the common 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 the so-called herd immunity.
However, experts warn that no one should feel invulnerable because the risk of lack of immunity remains high.
And the question of whether we will have to be immunized again next fall remains open.
Tags:
– .
