The MMR vaccine protects against measles, mumps, and rubella (German measles). Many children in the U.S. are immunized as infants and toddlers, but that doesn't guarantee lifetime protection. And not everyone gets vaccinated as a child. Many adults move to the U.S. from countries without immunization programs.
When infected with Lycanthropy, or engaged in Beast Form as a result of Hircine's Ring or completing the Companions questline, persons become fully immune to vampirism. Argonians are naturally resistant to disease, and are 50% less likely than Men or Mer to contract vampirism. PC Disease resistance may fail to prevent vampirism. 2  It is also possible to contract at least one disease (Bone Break Fever) as a vampire, despite vampires being listed as having 100% disease resistance. 3  PC In some cases, becoming a vampire does not grant the Vampire's Sight ability.
Dean meets Boris, and tries to stab him with the dead man's blood, but Boris is too quick. Before Boris can kill Dean, all the vampires collapse, Dean included. He has a shared vision of the Alpha vampire, and perceives that the Alpha wishes to build an army. When he awakes, Dean fights the vampires in the nest. Vampires are one of only two types of enemy in the show that can be cured, the other being demons. 2  However, unlike with demons, there is a time limit on when a vampire can be cured due to the requirement that the vampire not drink blood and the intense bloodlust they feel.