Robert Klatt

Some people do not contract the coronavirus despite being at high risk. A study now shows the reason for this “immunity”.

London (England). According to data from Johns Hopkins University (JHU), over 258 million people (as of November 24, 2021) have been shown to be infected with SARS-CoV-2. However, scientists at University College London (UCL) have observed that some people do not contract the coronavirus, even though their work in the hospital is associated with a high risk of infection. Now the researchers working with Leo Swadling have published a study in the journal Nature that aims to explain the reasons for this.

The study included 58 people who worked in hospitals in London during the first wave of the Covid-19 pandemic and who did not become infected despite the high risk of infection. No PCR test was positive in any of the test subjects for a period of four months. Antibodies were also not found, although colleagues with whom the test subjects worked closely had been infected with corona.

Termination of T-Cell Infection?

The scientists found increased T-cell values ​​in 20 test subjects. The immune protein IFI 27, which is a typical signature of an early infection with SARS-CoV-2, was detected in 19 test subjects. According to the study, the presence of the immune protein is an indication of an aborted infection. In this case, the coronavirus would have been fended off before it could cause damage to the body.

“I’ve never seen anything like it. It is very surprising that T cells could be able to control an infection so quickly, ”says immunologist Shane Crotty of the La Jolla Institute for Immunology.

Inactivated protein clusters of the virus

According to the study authors, this is very likely due to the fact that the T cells switched off a protein cluster that is necessary for the virus to reproduce. This thesis is also supported by the fact that a larger proportion of the 58 test subjects had T cells in their blood that recognize this cluster than in the comparison group that was infected with SARS-CoV-2.

The scientists have also recognized that T cells that recognize the protein cluster were already present in the subjects’ blood samples that were taken before the occurrence of SARS-CoV-2. According to the study, these could have resulted from infections with other coronaviruses. In medicine one speaks of a cross infection.

No evidence of contact with SARS-CoV-2

In science, however, the methodology of the study is also criticized because there is no evidence that the 58 test subjects actually had contact with SARS-CoV-2. According to the immunologist Donna Farber, it is therefore problematic to assume that the T cells prevented infection. The co-author Mala Maini also confirms that the team has no direct evidence of an interrupted corona infection in the test subjects. However, the course of the Covid-19 pandemic in Great Britain is well documented and the study authors therefore assume that it is no coincidence that at a time when there are many Covid-19 patients in British hospitals, an increase in T cells in the blood of the Subjects were discovered. “The timing is so clear,” explains Maini.

Restrictions on the delta variant?

The authors also state that their theory, if correct, does not have to apply to the delta variant of the virus. In addition, the infection could only be interrupted in people who have come into regular contact with respiratory viruses. The scientists were therefore quick to assume that an earlier infection with another coronavirus would also protect against SARS-CoV-2.

As the biomedical scientist Alexander Edwards of the University of Reading explains, despite all the concerns, the study can definitely help in the fight against the Covid-19 pandemic. According to him, the study design enables the development of a completely new type of vaccine. “A vaccine that boosts T-cell immunity to various viral protein targets that are shared by many different coronaviruses would complement our vaccines that induce neutralizing antibodies,” explains Edwards.

Nature, doi: 10.1038/s41586-021-04186-8


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