American scientists have found that people who have had COVID-19 often have a long-term violation of cellular immunity. This can increase susceptibility to secondary infections or prevent the development of full-fledged protection against SARS-CoV-2. The results of the study are published in the Journal of Clinical Investigation.
Experts from the University of Alabama at Birmingham conducted an observational study to find out how the cellular immune response changes in patients who have had COVID-19. To do this, they took blood samples from 46 people who needed hospitalization and from 39 who were treated at home. From the samples, the scientists isolated certain subsets of immune cells and analyzed their surface markers. The data were compared with healthy people from the control group.
Based on the results obtained, it was possible to create a picture of how each person’s immune system reacts to infection and how it behaves during recovery.
It turned out that many patients with COVID-19 have depleted immune cells, so they are less resistant to secondary infections and prevent the development of full-fledged protective immunity to the coronavirus.
According to the authors, this information should be taken into account when developing and modifying vaccines and treatments for COVID-19 and interpreting the immune responses generated by participants in candidate vaccine trials.
The researchers analyzed the change in cellular immunity in two ways: by continuously observing surface markers in the samples and by directly comparing the frequencies of these markers between the first and second blood tests.
The study included an in-depth characterization of the activation and depletion phenotype of CD4 + T cells, CD8 + T cells, and B cells. B- and T- cells in both groups of patients corresponded to the activation and cellular depletion phenotype during the first two months of infection. In those treated at home, activation and cellular depletion markers increased over time.
What was unexpected was that patients with mild symptoms of COVID-19 had immune regulation disorders that persisted longer than those hospitalized. This was especially pronounced in the elderly.
“These results indicate the nature of changes in the adaptive immune system in COVID-19 and suggest longer-term effects of impaired immunity, including to SARS-CoV-2,” the study authors write.
They note that their work is the first description of persistent immune dysregulation due to COVID-19 in recovering patients. Now the search continues for an answer to the question of whether the observed immunological changes are associated with the symptoms of the so-called “long-term COVID.”