Neutrophil Extracellular Traps (NETs) (IMAGE) University of Utah Health Caption During COVID-19, infection fighting-cells emit Neutrophil Extracellular Traps (NETs, purple), a sticky web-like substance, to capture invading viruses. An overactive NET response may contribute to blood clots and complications that arise in severe COVID-19. Credit Christian Con Yost Usage Restrictions With credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.