How quickly a person’s immune system responds to coronavirus infection plays an important role in determining the severity of diseases.
Cambridge researchers studied 207 people who tested positive for Covid-19 over a three-month period and found that people without symptoms or mild cases had a strong immune response shortly after being infected.
But people with severe cases requiring hospitalization had a diminished immune response, leading to a delayed and weakened attempt to fight the virus.
This undercooked response to the infection is characterized by inflammation of several organs, which occurs immediately after someone catches the coronavirus.
Scientists say abnormalities in immune cells can be behind the sluggish response to viral infection as well as the inflammatory response of the body, and can contribute to serious illnesses and also ‘long’ Covid ‘.
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How quickly a person’s immune system responds to coronavirus infection plays an important role in determining the severity of the disease, according to a study (file)
Dr Paul Lyons, senior co-author of the study at the Cambridge Institute of Therapeutic Immunology and Infectious Disease (CITIID), said: ‘Our evidence suggests that the journey to severe Covid-19 may be determined immediately after infection, or at last. becomes about the time they begin to show symptoms.
‘This finding could have major consequences for the management of the disease, as it suggests that we should start treatment to stop the immune system very early, and even preventively in high-risk groups that are screened and diagnosed. before symptoms develop. ‘
There is no cure for Covid-19, but treatment has improved since its inception in late 2019 in China.
Researchers from the University of Cambridge recruited a series of people who tested positive for the virus to see how the immune system’s response affects a person’s prognosis.
These individuals ranged from asymptomatic health workers to patients in need of ventilation.
In the study, which has not yet been peer-reviewed but is available as a pre-print on medRxiv, the team analyzed blood samples taken regularly over three months.
They compared the samples with the samples taken from 45 healthy people.
Researchers found evidence of an early, robust adaptive immune response in the infected individuals whose disease was asymptomatic or slightly 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 people without symptoms or mild cases had a robust immune response immediately after being infected (file)
These people produced the immune components in greater numbers than patients with worse Covid-19, and within the first week of infection.
After this, the numbers quickly returned to normal.
There was no evidence in these individuals of systemic inflammation that could lead to damage to multiple organs.
In patients admitted to the hospital, the early adaptive immune response was delayed and there were severe abnormalities in a number of white cell carriers.
Researchers believe this suggests that an abnormal inflammatory component of the immune response is present even during diagnosis in individuals leading to serious illnesses.
Professor Derek Hill of UCL, who was not involved in the study, said: ‘This article … finds that there were early blood tests signed related to the subsequent course of the disease, from only a mild illness to severe symptoms.
‘Furthermore, there is an indication of a signal in the blood tests about those who can get COVID for a long time.
‘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 help make treatment decisions. ‘
The team also found that key 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 illness, as well as to correlate with their risk of Covid-19-associated death.
The study also provides clues to the biological underlying cases of long covid – where patients experience symptoms of the disease, including fatigue, a few months after infection, even if they are no longer positive for the virus.
The team found that profound changes in many immune cell types often persist weeks or even months after SARS-CoV-2 infection, and these problems have resolved themselves very differently, depending on the type of immune cell.
While some recover as the systemic inflammation resolves on its own, others recover even if there is persistent systemic inflammation.
However, some cell populations remain markedly abnormal or show only limited recovery, even after systemic inflammation has disappeared and patients have been discharged from the hospital.
Dr Laura Bergamaschi, the first author of the study, said: ‘It is these populations of immune cells that still show abnormalities, even though everything else seems to have resolved itself that may be of interest in long COVID.
‘For some cell types it may just be slow to regenerate, but for others, including some types of T and B cells, it seems that something is driving their activity.
“The more we understand this, the better the chance that we can better treat patients whose lives are still contaminated by the after-effects of COVID-19.”