Back in 1986, he penned a letter to parents pleading them to vaccinate after his daughter Olivia died in 1962 before the vaccine was avalible. In the letter, Dahl expresses concern that he has seen some parents resisting the vaccine because "it is not yet generally accepted that measles can be a dangerous illness." He writes: "believe me, it is. In my opinion, parents who now refuse to have their children immunised are putting the lives of those children at risk." Amidst the warnings from the Ministry of Health about travelling in or around Auckland and with 905 measles cases in NZ so far, the letter is doing the rounds again and you can read it below. Don't forget, if you are under 50 years and have never had a measles vaccine you can get vaccinated for free.