Utilize the input text as a context reference, choose the right relationship between MedImmune and AstraZeneca from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

Companies like Pfizer, Sanofi, Merck, AstraZeneca and MedImmune continue to disinfect with a safe SteraMist BIT chemical protecting their operator, facility and the environment, while providing the confidence to the American population that we will produce sterile vaccines.

Answer: parent_organization