Thrombosis is involved in immune system functioning. An example of this would be the role platelets play. Platelets bind to the pathogen, thus removing them from circulating in the blood. It also allows serotonin to be secreted, bringing T-cells and neutrophils into play. In those with covid-19, thrombosis, along with inflammation, was present. A group of white blood cells was found around small vessels that contained blood clots and neutrophils. These blood clots are a result of thrombosis and the surrounding white blood cells resulted in inflammation. These factors come together to be known as thromboinflammation.