An antibody, also known as an immunoglobulin, is a large Y-shaped protein produced by the immune system to neutralize pathogens such as bacteria and viruses.

A blood transfusion is a medical procedure where blood is transferred from one person (the donor) to another person (the recipient).

The Wikipedia page on the COVID-19 pandemic provides a comprehensive overview of the ongoing global pandemic caused by the novel coronavirus.

ELISA (enzyme-linked immunosorbent assay) is a widely used laboratory technique used to detect and quantify the presence of specific proteins, antibodies, or antigens in a sample.

The Wikipedia page on Immunity (medical) provides a comprehensive overview of the concepts and mechanisms of immunity in the field of medicine.

Immunoglobulin G (IgG) is a type of immunoglobulin, also known as an antibody, that is found in the bloodstream and helps protect the body against infections.

Informed consent is a principle in medical ethics, medical law and media studies, that a patient must have sufficient information and understanding before making decisions about their medical care.