Representation for vaccine | Credits: Google Images
Representation for vaccine | Credits: Google Images

Beyond Vaccines: Exploring Immune Dynamics in Long COVID – Latest Study Insights!

A team of scientists attempted to study the etiology of long coronavirus disease (long COVID) recently by using blood samples from patients with and without clear long COVID clinical trajectories.

As per, the study also took note of the immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) through ‘omics’ approaches and serological assays.

The findings of the study were published in the journal Nature Immunology.

Importance of the study

According to the reports, the severity and spread of the coronavirus disease 2019 (COVID-19) pandemic have been put to rest through combined efforts worldwide to produce vaccines against SARS-CoV-2 and administer vaccination among large portions of the global population.

However, the new variants do not appear to have morbidity and mortality rates as those of the initial wave of COVID-19.

The long COVID, or post-acute sequelae of COVID-19 (PASC), continue to be a major health concern, with persistent symptoms such as fatigue, myalgia, dyspnea, and long-term impacts on cardiovascular, neurological, and muscular health, reported.

The reason for the long-term symptoms could be the immune perturbations due to infection of SARS-CoV-2, according to recent studies.

The total SARS-CoV-2 infections that resulted in long COVID are about 10 percent or more, the researchers are still unclear about the etiology and pathophysiology of it.

Doses of vaccination for COVID-19 | Credits: Reuters

As per, the role of T cells in long COVID is yet to be fully known, whereas its role in the pathogenesis of and immunity against SARS-CoV-2 is well understood by the researchers.

About the study

Serological assays and an ‘omics’ approach were used by the researchers to properly understand and specify global immunity and specific immunity against SARS-CoV-2 with the help of blood samples of patients with and without clinical symptoms of long COVID.

The study aimed to identify and specify the immune features mainly associated with long COVID to recognize the pathological mechanisms of the disease, reported.

Cytometry by the time of flight (CyTOF) serological assay, plasma proteomics, ribonucleic acid (RNA) sequencing, and single-cell RNA sequencing (scRNAseq) were used to specify the phenotype of T cells in matched sections of COVID-19 patients suffering from long COVID and patients who had fully recovered.

The powerful tool, cytometry by time of flight (CyTOF) serological assay or Mass Cytometry is a newly introduced technology that by using mass spectroscopy, measures the abundance of metal isotope labels on antibodies and other tags on single cells.

Blood samples were obtained from a section of well-characterized COVID-19 patients eight months after the SARS-CoV-2 infection but before reinfection or COVID-19 vaccination.

Findings of the study

According to reports, the results were revealed when a comparison was made between the COVID-19 patients who had fully recovered, with the long COVID patients who showed evidence of immune dysregulation and systemic inflammation.

It was shown with The distribution of T cells showing global differences expressed continued immune responses. Sex-specific signals were also shown by the cytolytic subsets.

Individuals with long COVID had a significantly lower frequency of anti-SARS-CoV-2 cytotoxic T cells and mis-coordinated B and T-cell responses against SARS-CoV-2.

According to the report, those individuals also appeared to have heightened antibodies against SARS-CoV-2 and a higher frequency of helper T cells ready to migrate toward inflamed tissue, reported.

Moreover, sex-specific dissimilarities were also noticed, where female patients having long COVID had lower frequencies of naive helper and cytotoxic T cells along with higher levels of terminally differentiated effector memory helper and cytotoxic T cell demonstrating cytolytic markers and homing receptors for inflammatory tissue.

Overall, the ‘omics’ approach used in the study pointed out that persons with long COVID reflected major gene expression changes in not only the helper T cells and cytotoxic T cells but also B cells and monocytes, along with phenotypic perturbations in the helper and cytotoxic T cells overall and in those specifically against SARS-CoV-2, reported.

Conclusion gathered from the study

In conclusion, important immune-associated changes and phenotypic alterations in T cells and other immune cells were noticed among the patients with long COVID, which could be the mechanistic basis for the persistent and wide-ranging symptoms associated with long COVID.

Between humoral and cellular adaptive immunity involving B and T cells, a miscommunication or error in crosstalk could contribute to inflammation, immune dysregulation, and the clinical symptoms characteristic of long COVID, reported