Prolonged Immune Response Linked With Post-COVID-19 Blood Clots

Survivors of the disease have been found to be at an increased risk of blood clots or strokes due to a prolonged immune response caused by the virus.

A recent study published in the journal eLife has discovered that serious complications caused by blood clots, including heart attacks and strokes, experienced by some survivors of COVID-19 may be caused by an immune response that lingers in the blood vessels.

The research was conducted by investigators from the Lee Kong Chian School of Medicine.

"During the initial stages of infection, SARS-CoV-2, the virus that causes COVID-19, may attack the lining of the blood vessels which can trigger inflammation and an immune response. This can result in blood vessel damage in the short term," Florence Chioh, a first author on the study said. "For our study, we wanted to investigate what happens in the blood vessels of COVID-19 survivors over the longer term."

For the study, investigators collected blood samples from survivors of COVID-19 within 1 month of their recovery and discharge from the hospital.

Findings showed that the survivors of COVID-19 had two times as many damaged blood vessels in their blood in comparison to healthy individuals. Those with conditions such as hypertension or diabetes, which are known to damage blood vessels, had even more floating in their blood.

Additional findings demonstrated that the survivors had an abundance of cytokines, an inflammatory protein that is produced by immune cells. T cells, a type of immune cell, were also found in unusually high numbers even when the virus was already cleared.

The investigators hope that their findings can help to explain why some who survive COVID-19 report lasting symptoms and why some may even experience strokes or heart attacks for long periods of time after recovery.

"Our work suggests that COVID-19 patients, especially those with underlying chronic conditions, may benefit from close post-recovery monitoring," Christine Cheung, a senior author on the study said. "This would help identify high-risk individuals who may need blood thinners or preventative therapy to protect them from debilitating blood-clotting complications."