This study examined the efficacy of inoculation treatments in preventing anti-vaccination propaganda. Study predictions were tested in an independent-group experiment (N = 165), wherein participants were randomly assigned to a fact-based inoculation or a logic-based inoculation or a control message, with an excerpt from an anti-vaccination conspiracy film, Vaxxed, used as a counterattitudinal attack message. The results indicated that both inoculation treatments (fact-based and logic-based) were effective at instilling resistance to counter-persuasion, as compared to the control condition, and both types of inoculation messages were equal in their potential to facilitate resistance. In addition, we tested whether inoculating participants against an anti-vaccination conspiracy would help prevent the endorsement of other conspiracy theories. The data revealed that inoculating against one type of a conspiracy did not foster protection against other types of conspiratorial ideas, and, similar to previous research, endorsing one type of a conspiracy theory was positively associated with the endorsement of other conspiracies. These and other results are discussed along with their implications, limitations, and future research directions.