Why some people get ‘long COVID’ while others don’t

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In a recent study, researchers have delivered crucial insight into the lasting immune system damage caused by COVID-19.

They showed that people’s immune systems were significantly altered six months after their COVID-19 infection.

The study is from the University of Adelaide. One researcher is Professor David Lynn.

The immune cells and gene expression experienced during this post-infection period hold clues to the intriguing “Long COVID’ symptoms affecting some patients.

By taking a deep dive into the immune cells in these patients, the team found some new players linked to the disease, and these may help understand why some people have more severe disease or get Long COVID.

It involved an in-depth assessment of a South Australian patient cohort, termed “COVID-19 SA”.

The immune systems of 69 participants between 20 and 80 years of age were examined over a 6-month period, following infection with the original strain of SARS-CoV-2, the virus that causes COVID-19.

Of the total cohort, 47 were recovering from a mild infection, six were from moderate and 13 were recovering from severe or critical COVID-19 disease.

The unique analysis examined antibody responses, the expression of thousands of genes in the blood, and approximately 130 different types of immune cells, via blood samples taken at 12, 16 and 24-weeks post infection.

The results showed that the immune system of people previously infected with SARS-CoV-2 was strongly changed until at least six months post-infection.

The team found substantial dysregulation of immune cell numbers that were strongest at 12-weeks post-infection but was still evident in most cases for up to six months and potentially even longer.

In addition to an increased number of immune cells and antibodies, there was also strong dysregulation of gene expression, particularly in those genes linked to inflammation.

Gene expression refers to information stored in DNA that regulates how cells respond to changing environments. This can include controlling when and how much response is made against an invading virus.

The team says deep immunophenotyping will develop the understanding of how rare immune cells help repair the damage and set up immunity to COVID-19.

The study didn’t have the capacity to analyze the extent to which participants were experiencing the symptoms commonly associated with Long COVID, such as fatigue, shortness of breath, chest pain and brain fog.

The team says it’s likely these symptoms are related to the upheaval of immune cells and gene expression.

If you care about long COVID, please read studies about lung maintains long-term memory of COVID infection and findings of long COVID linked to more bacteria in your mouth.

For more information about long COVID and your health, please see recent studies about your eyes can show signs of ‘long COVID’ and results about how many people get ‘long COVID?’ More than half, study finds.

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