Patients who experienced severe COVID-19 symptoms are likely to suffer long-term effects on their immune system, according to research from Linköping University.
A study conducted by researchers at Linköping University has suggested that infection by the SARS-CoV-2 virus has significant long-term effects on those who suffered severe COVID-19 symptoms. The immune cells of patients who needed to receive hospital care for Covid-19 early in the pandemic have been found to still be affected up to eight months after the infection.
The results have been published in Frontiers in Immunology.
Severe COVID-19 symptoms are more damaging than expected
“We see that severe COVID-19 symptoms have long-lasting negative effects on the immune system. Obviously, the immune system is affected pretty badly when people are in hospital sick with COVID-19, but we had not anticipated that the effects would persist as long as seven to eight months later,” said Francis Hopkins, postdoc in the Department of Biomedical and Clinical Sciences at Linköping University.
When the immune system starts to fight against Covid-19, several types of important cells are used. White blood cells and B cells form antibodies that recognise and bind to parts of the virus. Several types of T cells can also help to kill infected cells. In their study, the Linköping University researchers examine whether cases of infection with severe COVID-19 symptoms can have long-term, damaging effects on the body’s immune cells.
The researchers analysed 46 patients who had experienced severe COVID-19 symptoms and subsequent care at Vrinnevi Hospital in Norrköping, Sweden. These participants were analysed against a control group of 31 healthy subjects.
The researchers analysed blood samples taken from the patients when they were first admitted to hospital. Further samples were taken after two weeks, six weeks and six to eight months later. The researchers looked at the properties of the virus-specific T cells, they also examined whether the disease had a general effect on all T cells.
“The effects on the T cells of the immune system are interesting and mixed. Some of them are still activated long after the disease episode, while others are ‘fatigued’ and cannot function normally. We see similar effects on patients with a chronic HIV infection. The question is: why are these effects still present after so long?” asked Marie Larsson, professor of virology at the Department of Biomedical and Clinical Sciences at Linköping University, and leader of the study.
All patient antibodies developed in first three weeks
During the early phases of the pandemic, scientists from Linköping University helped to develop clinical tests that could be used to analyse patient samples. In these early stages, it was not known where different people’s immune systems differed in their ability to form antibodies against the infection. It was also unknown whether this would affect the likelihood of an induvial experiencing severe COVID-19 symptoms.
This study has shown that all patients developed antibodies against the virus in the first two to three weeks after first showing signs of symptoms.
“We see that all the patients in the study developed antibodies against SARS-CoV-2. The levels of these antibodies started to fall after six months,” says Melissa Govender, a postdoc in the group.
