How quickly a person’s immune system responds after infection with the coronavirus plays a critical role in determining the severity of the disease, a study shows.
Cambridge researchers studied 207 people who tested positive for Covid-19 over a three-month period and found that those with no symptoms or mild cases showed a robust immune response shortly after becoming infected.
But the people with severe cases that required hospitalization had a diminished immune response, which led to a delayed and weakened attempt to fight the virus.
This underheated response to the infection is characterized by inflammation of several organs, which occurs immediately after a person has contracted the coronavirus.
Scientists say abnormalities in immune cells may be the cause of the body’s flaccid response to viral infection and the body’s inflammatory response, and may contribute to serious illness as well as ‘long Covid’.
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How quickly a person’s immune system responds after infection with the coronavirus plays a crucial role in determining the severity of the disease, study finds (file)
Dr. Paul Lyons, senior co-author of the Cambridge Institute of Therapeutic Immunology and Infectious Disease (CITIID) study, said: ‘Our evidence suggests that the journey to severe Covid-19 can be diagnosed immediately after infection, or at the time they start showing symptoms.
This finding could have major implications for how the disease should be treated, as it suggests that we need to start treatment to avoid damaging the immune system very early, and perhaps even preventively in high-risk groups being screened and diagnosed. . before symptoms develop. ‘
There is no cure for Covid-19, but treatments have improved since it first showed up in China in late 2019.
The University of Cambridge researchers recruited a series of people who tested positive for the virus to see how the immune system response affected a person’s prognosis.
These individuals ranged from asymptomatic health professionals to patients requiring ventilation.
In the study, which has not yet been peer-reviewed, but is available as pre-print medRxiv, the team analyzed blood samples taken regularly over three months.
They compared the samples with those from 45 healthy people.
Researchers found evidence of an early, robust adaptive immune response in those infected individuals whose disease was asymptomatic or mildly symptomatic.
An adaptive immune response is when the immune system identifies an infection and then produces T cells, B cells, and antibodies specific for the virus to fight back.
Cambridge researchers studied 207 people who tested positive for Covid-19 over a three-month period and found that those with no symptoms or a mild case showed a robust immune response right after becoming infected (file)
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A ‘cytokine storm’ is a process by which the immune system becomes confused and attacks healthy tissue instead of just the virus.
In many severe Covid cases, this is proving fatal, and finding a way to moderate this process has been a priority for doctors.
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These people produced the immune components in greater numbers than patients with more severe Covid-19, and within the first week of infection.
After this, the numbers quickly returned to normal.
There was no evidence of systemic inflammation that could lead to multi-organ damage in these subjects.
In patients who had to be hospitalized, the early adaptive immune response was delayed and there were serious abnormalities in some subgroups of white blood cells.
Researchers say this suggests that an abnormal inflammatory component of the immune response is present even around the time of diagnosis in individuals developing into severe disease.
Professor Derek Hill of UCL, who was not involved in the study, said: “ This article … establishes that there are signatures in early blood tests associated with the subsequent course of the disease, from having mild to severe disease. symptoms.
Plus, there’s a hint of a signal in the blood tests about those who might get COVID.
These are interesting findings, but it is important to note that a much larger study would be needed to determine whether the blood test ‘signatures’ identified by the authors are reliable predictors of the course of the diseases, and whether such information can be used to assist in treatment decisions. ‘
The team also found that important molecular signatures produced in response to inflammation were present in patients admitted to the hospital.
They say these signatures could potentially be used to predict the severity of a patient’s disease, as well as correlate with their risk of Covid-19-associated death.
The study also provides clues to the biology underlying cases of long-term Covid – where patients report experiencing symptoms of the disease, including fatigue, for several months after infection, even when they no longer test positive for the virus.
The team found that profound changes in many immune cell types often persisted for weeks or even months after SARS-CoV-2 infection, and these problems resolved themselves very differently depending on the immune cell type.
While some recover when the systemic inflammation resolves itself, some others recover even with persistent systemic inflammation.
However, some cell populations remain remarkably abnormal or show limited recovery even after the systemic inflammation has resolved and patients are discharged from the hospital.
Dr. Laura Bergamaschi, the study’s lead author, said, “ It is these populations of immune cells that still show abnormalities, even when everything else appears to be resolved, that could be of interest in long COVID.
“For some cell types, they may just regenerate slowly, but for others, including some types of T and B cells, it seems that something continues to drive their activity.
“The more we understand this, the more likely we will be able to better treat patients whose lives are still affected by the aftereffects of COVID-19.”