Should we now continuously vaccinate against the coronavirus?

Booster shots are necessary because, over time, the number of antibodies in our blood decreases. In the case of mRNA vaccines, this usually occurs about six months after immunization against the coronavirus.

For other vaccines, such as Johnson & Johnson’s single-use vaccine, the German Standing Committee on Immunization (Stiko) recommends booster even a little earlier.

But will it always be like this? Do we have to prepare so that in the future we will need a booster shot every six months or always in the fall, similar to the flu?

The doctors still don’t know the answer to this question, because they lack experience and data.

Several aspects come into play here: Vaccines will likely have to be adapted to new virus variants in the future, similar to the seasonal flu vaccines that already exist today. There are already numerous new vaccines in development that take into account certain mutations of the delta variant, for example.

Is SARS-CoV-2 becoming endemic?

Furthermore, the subsequent course of the pandemic plays a decisive role. It is not clear if the pandemic will end after the fourth or fifth wave, or if SARS-CoV-2 and its variants will become endemic, that is, they will appear regularly in certain regions and will remain with us for decades.

The issue of group immunity is closely related to this. Will we get it soon? Will it occur through vaccination or perhaps through involuntary contagion, such as the one that is already emerging in large areas of Africa? Given current incidence rates, something like this could happen in Europe as well.

Memory T cells would generate ‘pre-immunity’ against COVID-19 in part of the population of Ecuador

Do not forget the memory T cells

But it’s not just antibodies that we need to consider when considering our immunity. This is indicated by a study not yet peer-reviewed and published by a large team of researchers from Great Britain and Singapore in the journal Nature on November 10, 2021.

The researchers had found healthcare workers at high risk of exposure to SARS-CoV-2, but who had not had any recognizable illness such as COVID-19 or positive PCR test results for months. All 58 employees also went undetected in a serological antibody test.

Immunity without detectable antibodies

The researchers found that these “seronegative healthcare workers (SN-HCW)” had more multispecific memory T cells than a comparison group working at significantly lower risk of exposure.

These T cells are directed in particular against the so-called transcription and replication complex (RTC), which is primarily responsible for the replication of the virus.

In turn, an increase in the amount of the IFI27 protein was found in all 58 people, which is considered an indication of a very early SARS-CoV-2 infection. From this, the researchers concluded that all affected healthcare workers had had an aborted or “abortive” coronavirus infection.

COVID-19, cold, allergies or flu, what are their differences?

Therefore, T cells may have interrupted the coronavirus infection at an early stage. It’s still unclear where the 58 healthcare workers got their unusually strong T-cell immunity – it could be the result of a previous infection with another coronavirus, such as a cold virus.

Will group immunity arrive?

One possible consequence of this is that repeated exposure to coronaviruses, for example if SARS-CoV-2 really became endemic and we repeatedly came into contact with some pathogens, this could make our immune system better position itself against it: either with antibodies or also with T cells. This would definitely bring us closer to group immunity.

However, the researchers strongly recommend not neglecting yourself because of the discovery. No one should feel safe or assume they are immune to SARS-CoV-2. The risk of not being immune is very high.

The question remains whether we will have to reinforce our vaccines again next fall. That will be seen when the time comes. (I)