"In the case of COVID-19 vaccines, several makers have used HEK293 to generate what are called "viral vectors." These are weakened versions of common cold-causing adenoviruses that are loaded with the genetic instructions for human cells to manufacture a surface protein of the coronavirus. This elicits an immune response that the body remembers when it encounters the real coronavirus. Three vaccines that are in advanced trials use HEK293 lines—the Oxford vaccine co-developed with AstraZeneca, China's CanSino Biologics vaccine and Russia's Gamaleya Institute vaccine. Johnson & Johnson uses the other major fetal cell line, PER.C6. Several other companies, such as Moderna and Pfizer, have used HEK293 to develop "pseudoviruses" to test their drugs. Vaccines against Ebola and tuberculosis, as well as gene therapies, have also been created with HEK293 cells, said Graham. "I take great satisfaction from the fact that the cells I created nearly 50 years ago have played a major role in numerous advances in biomedical research and in the production of vaccines and medicines," said the professor, who dislikes commenting on the controversy that periodically emerges over their origin."