Long Covid patients suffer from chronic symptoms such as fatigue or shortness of breath. As researchers have discovered, this is to some extent due to a part of our immune system called the complement ...

Complement component 3, often called C3, is an essential protein of the immune system. This protein plays a vital role in the body’s innate immune system, providing the first line of defense against ...

A complement C4 (also known as a complement component 4, or simply C4) is a test to measure the level of C4 proteins you have in your blood. These proteins play a role in how your immune system ...

Most people infected with the SARS-CoV-2 virus recover after the acute illness. However, a significant proportion of infected individuals develop long-lasting symptoms with a wide range of ...