SARS-CoV-2: Harmless, cold-causing coronaviruses provide protection
The COVID-19 pandemic continues to have a firm grip on large parts of Europe and now South Africa again. The number of people who are infected with the SARS-CoV-2 coronavirus is increasing and increasing and more and more people are becoming seriously ill and have to be treated in hospital – sometimes by intensive care. Researchers are now reporting that harmless, cold-causing coronaviruses can protect against the disease.
Infections with SARS-CoV-2 or vaccinations, on the other hand, lead to strong antibody reactions against the new coronavirus. Immune reactions against other human coronaviruses, which mostly only lead to harmless colds, also confer a certain protection against SARS-CoV-2. As researchers from the University of Zurich (UZH) show, such cross-reactions are an important piece of the puzzle for comprehensive coronavirus immunity.
Immune protection of the population is crucial
A research team led by UZH has now identified another component that contributes to SARS-CoV-2 immunity: existing antibody reactions against other, harmless coronaviruses.
“People who have pronounced immune responses against human coronaviruses are also protected to a certain extent against infection with SARS-CoV-2,” explains Alexandra Trkola, head of the Institute for Medical Virology at UZH.
The study results were recently published in the journal “Nature Communications” released.
Human coronavirus currently circulating
As part of the study, the researchers used a specially developed test method to analyze the amount of different antibodies against the four other currently circulating human coronaviruses in the blood serum of 825 donors from the time before the occurrence of SARS-CoV-2.
On the other hand, they examined 389 samples from donors who had become infected with the new coronavirus. This analysis, combined with computer-aided modeling, enables precise predictions of how well the antibodies bind to invading viruses and neutralize them.
The scientists were able to show that people who were infected with SARS-CoV-2 had lower levels of antibodies against the common cold coronavirus. In addition, SARS-CoV-2 infected people with high antibody levels against the harmless coronaviruses had to be hospitalized less often.
“According to our results, a stronger antibody reaction against human coronaviruses also leads to higher amounts of antibodies against SARS-CoV-2. A person who has immunity against harmless coronaviruses is thus better protected against severe courses of SARS-CoV-2 infections, “said Trkola. This is known as a cross-reaction. This also occurs in the immune reaction of T cells, the second pillar of our immune system.
Shortened and mitigated course of the disease
People only have complete protection against SARS-CoV-2 at the beginning after an infection or after an effective vaccination. Because then the amounts of antibodies against the pathogen are still very high.
If their concentration drops over time, an infection is no longer prevented, but the memory cells reactivate the immune system – both antibody production and T-cell defense – quickly.
“Immune reactions specifically directed against SARS-CoV-2 that originate from memory cells are of course far more effective than cross-reactive ones. But although the protection is not complete, cross-reactions shorten the course of the disease and lessen its severity. And that’s exactly what we achieve with vaccinations, only much, much more efficiently, ”Trkola emphasizes.
Comprehensive protection against coronaviruses
It is not yet clear whether the cross-reactivity also works the other way round. So whether immunity against SARS-CoV-2 – for example through a vaccination – also protects against other human coronaviruses.
“If SARS-CoV-2 immunity also offers a certain protection against infection from other coronaviruses, we would come a big step closer to comprehensive protection against coronaviruses, including newly emerging variants,” says the virologist.
According to the experts, this assumption is also supported by the fact that a cross-reactive protective effect is not only based on antibodies, but very likely also on T cells. (ad)
Author and source information
This text complies with the requirements of specialist medical literature, medical guidelines and current studies and has been checked by medical professionals.
- University of Zurich: Antibodies against harmless coronaviruses also support SARS-CoV-2 immunity, (accessed: November 27, 2021), University of Zurich
- Irene A. Abela, Chloé Pasin, Magdalena Schwarzmüller, et. al.: Multifactorial seroprofiling dissects the contribution of pre-existing human coronaviruses responses to SARS-CoV-2 immunity; in: Nature Communications, (veröffentlicht: 18.11.2021), Nature Communications
This article is for general guidance only and is not intended to be used for self-diagnosis or self-treatment. He can not substitute a visit at the doctor.