"Over the ensuing years, frozen vials of the cells were flown to hundreds of laboratories across the world, WI-38 is now one of the oldest and most widely available cell lines on the planet. As Hayflick has noted previously – although perhaps rather insensitively – as early as 1984, WI-38 had become “the first cultured normal human cell population to ever reach voting age”. Today the cells are routinely used to make vaccines against polio, measles, mumps, rubella, varicella zoster (chicken pox), herpes zoster, adenovirus, rabies and Hepatitis A. Why are the cells so special? And how can we justify continuing to use them?"