One study shows that how quickly a person’s immune system responds after coronavirus infection plays a crucial role in determining the severity of the disease.
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 had a strong immune response shortly after becoming infected.
But people with severe cases who needed hospitalization had a deteriorated immune response, which resulted in a delayed and weak attempt to fight the virus.
This poorly cooked response to infection is characterized by inflammation of several organs, which occurs immediately after a person catches the coronavirus.
Scientists say that immune cell abnormalities may be behind the weak response to the viral infection, as well as the body’s inflammatory response, and that they may contribute to a serious illness as well as a “long covid.”
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One study shows (file) how quickly a person’s immune system responds after coronavirus infection plays a crucial role in determining the severity of the disease.
Dr Paul Lyons, lead co-author of the Cambridge Institute for Therapeutic Immunology and Infectious Disease (CITIID) study, said: “Our evidence suggests that the journey to severe Covid-19 may be established immediately after infection. or at the latest around the time they begin to show symptoms.
“This finding could have important implications for how the disease should be controlled, as it suggests that we should begin treatment to stop the immune system from causing damage very soon, and perhaps even preventively in high-risk groups examined. and diagnosed before symptoms develop “.
There is no cure for Covid-19, but treatments have improved since it emerged in China in late 2019.
Researchers at Cambridge University recruited a number of people who tested positive for the virus to see how the immune system’s response affected a person’s prognosis.
These individuals range from asymptomatic health workers to patients who needed ventilation.
In the study, which has not yet been peer-reviewed but is available as a prepress at medRxiv, the team analyzed blood samples taken regularly for three months.
They compared the samples with the prey to 45 healthy people.
The researchers found evidence of an early and robust adaptive immune response in those infected individuals whose disease was asymptomatic or slightly symptomatic.
An adaptive immune response is when the immune system identifies an infection and produces virus-specific T cells, B cells, and antibodies to fight.
Cambridge researchers studied 207 people who tested positive for Covid-19 over a three-month period and found that those who had no symptoms or had a mild case had a robust immune response immediately after becoming infected. (file)
These people produced higher immune components than patients with more severe Covid-19 and during the first week of infection.
After that, the numbers quickly returned to normal.
In these individuals there was no evidence of systemic inflammation that could cause damage to multiple organs.
In patients who needed to be hospitalized, the early adaptive immune response was delayed and profound abnormalities occurred in several subsets of white blood cells.
The researchers say this suggests that an abnormal inflammatory component for the immune response is present even at the time of diagnosis in individuals progressing to severe disease.
UCL Professor Derek Hill, who did not participate in the study, said: “This paper … finds that there are signatures in the first blood tests that are associated with the later course of the disease, from having only mild to severe symptoms.
“In addition, there is a clue of a signal in blood tests on those who could have a long COVID.
“These are interesting findings, but it is important to note that a much broader study would be needed to determine whether the” signatures “of the blood tests the authors have identified are reliable predictors of the course of disease and whether this information could be used to help make treatment decisions “.
The team also found that key molecular signatures produced in response to inflammation were present in hospital-admitted patients.
They say these signatures could potentially be used to predict a patient’s disease severity, as well as correlate with their risk of death associated with Covid-19.
The study also provides clues about cases underlying the biology of long 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 alterations in many types of immune cells often persisted for weeks or even months after SARS-CoV-2 infection, and these problems were resolved very differently depending on the type of immune system. immune cell.
While some recover as systemic inflammation resolves, others recover even in the face of persistent systemic inflammation.
However, some cell populations remain markedly abnormal or show limited recovery, even after systemic inflammation has resolved and patients have been discharged from the hospital.
Dr. Laura Bergamaschi, the first author of the study, said: “It is these immune cell populations that still show abnormalities, even when everything else seems to have been resolved, which could be important. in the long COVID.
“For some cell types, they may regenerate slowly, but for others, including some T and B cell types, it seems that something continues to drive their activity.
“The more we understand this, the more likely we are to be able to better treat patients whose lives continue to be affected by the subsequent effects of COVID-19.”