MRC-5

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MRC-5 (Medical Research Council cell strain 5) is a line of human fibroblast cells taken from the lung tissue of a 14‑week‑old aborted male fetus. It was isolated in 1966 by J.P. Jacobs and colleagues, from the seventh doubling of the original tissue, and the cells stop dividing after about 45 population doublings. MRC-5 has been used to help make several vaccines, including hepatitis A, varicella (chickenpox), and polio. During the COVID-19 pandemic, some opponents claimed MRC-5 was an ingredient in the Oxford–AstraZeneca vaccine. A co-author of a related study said MRC-5 was used only for testing to see how the vaccine behaves in a normal human cell. The AstraZeneca vaccine was produced using a different cell line, HEK 293, derived from kidney cells of an aborted or miscarried female fetus; those cells are not present in the final vaccine.