In a new study from Flinders University, researchers have delivered crucial insight into the lasting immune system dysregulation caused by COVID-19.
They showed that people’s immune systems were strongly altered six months after their COVID-19 infection, with the immune cells and gene expression experienced during this post-infection period holding clues to the intriguing ‘Long COVID’ symptoms affecting some patients.
In the study, the immune systems of 69 participants between 20 and 80 years of age were examined over a six-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 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. Responses were compared to healthy controls.
The results show 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 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.
However, the team says it’s likely these symptoms are related to the upheaval of immune cells and gene expression.
The reason why some individuals are so harshly affected by Long COVID, while others are barely affected, remains a mystery.
Surprisingly, the research did not find a strong correlation between the severity of the infection and the severity of immune dysregulation post-infection. Immune dysregulation was evident even in those patients who experienced mild infections.
The study has also added further evidence that those who’ve had COVID-19 become immune to the virus.
If you care about long COVID, please read studies about risk of severe and ‘long’ COVID-19 may start very early and findings of even mild COVID-19 can lead to long-lasting illness.
For more information about long COVID and your health, please see recent studies about this heart failure drug may treat COVID-19 long-hauler symptom and results showing that 1 in 3 COVID survivors has long-term symptoms.
The study is published in medRxiv. One author of the study is Professor David Lynn.
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