The results of the work, which have been published in the magazine Frontiers in Immunologyconfirm immune alterations in cases of persistent covid, similar to those suffered by people with severe SARS-CoV-2 infection.
The lead author of the research is Mayte Coirasfrom the Immune Pathogenesis and Viral Reservoir Unit of the National Microbiology Center (CNM) of the ISCIII. Groups from the Infectious Diseases Area of the Biomedical Research Center in Network of the ISCIII (CYBERINFECTION) and various hospitals and universities in the Community of Madrid.
Post-Covid, Long Covid or Persistent Covid is the condition that some people develop after having a mild Covid-19 infection that does not require hospitalization, characterized by symptoms that may persist or worsen over time. The so-called persistent Covid is accompanied by changes in the immune system that can last for several months or years after having had the SARS-CoV-2 infection.
The authors of the research, at one of the doors of the National Microbiology Centre of the ISCIII. From left to right, Olivia de la Calle, Montserrat Torres, Clara Sánchez, Elena Mateos and Mayte Coiras, lead author of the work.
Analysis of immune response
With the aim of adding more scientific knowledge to this condition, whose origin and development are still not fully understood, and thus being able to define new therapeutic strategies, the research led by the ISCIII has compared the immune response in people with persistent covid with that of individuals hospitalized for covid-19 at different levels of severity, specifically analyzing the subtypes of CD4+ T lymphocyte immune cells, which are essential for the development of an effective immune response against the virus.
The results showed that people with persistent Covid who participated in the study had an immune system very similar to that of hospitalized patients with severe or critical Covid-19, with the presence in both groups of patients of an increase in pro-inflammatory cells and a reduction in their ability to fight infections.
Specifically, both people with persistent symptoms after infection and patients with ongoing severe infection showed lower levels of CD4 Th1 cells and an alteration in the capacity to express interferons and interleukins, all of which are essential mechanisms during an antiviral response.
Chronic inflammation and reduced ability to stop infections
The researchers explain that these immune changes could contribute to a chronic inflammatory state and greater vulnerability to infections in people with persistent Covid, a hypothesis that must be consolidated with new studies and that would suggest the need to develop new therapeutic strategies to ‘reprogram’ the immune response of these patients.
The group led by Mayte Coiras, the lead author of the paper, had already published a study in 2022 that revealed immune changes in people with persistent symptoms months after being infected. The article now published consolidates and adds new data to the existence of an altered antiviral immune response in so-called persistent Covid.
According to the author, the immune response in these people “is either not effective in completely eliminating the virus, or it remains active after the infection is over, as occurs in some autoimmune diseases. The symptoms of persistent Covid could be due to an unnecessary and prolonged immune response, or to insufficient defences to completely defeat the virus.” Further research will be needed to assess whether persistent Covid could be considered an inflammatory or autoimmune disease.
Article reference:
(2024) Different polarization and functionality of CD4+ T helper subsets in people with post-COVID condition. Front. Immunol. 15:1431411. doi: 10.3389/fimmu.2024.1431411.
