An antigen is a foreign substance that elicits a specific immune response or that itself is the target of such an immune response.
Detailed description
Antigens are generally foreign substances. They are recognized by antibodies and certain receptors on immune cells. Proteins, carbohydrates and lipids can function as an antigen.
In the years of the COVID-19 pandemic, the effectiveness of government-ordered measures to contain the pandemic, such as regular testing and the wearing of medical masks, was repeatedly called into
