The topic of vaccine safety became prominent during the mid 1970s with increases in lawsuits filed on behalf of those presumably injured by the diphtheria, pertussis, tetanus (DPT) vaccine. Legal decisions were made and damages awarded despite the lack of scientific evidence to support vaccine injury claims. As a result of these decisions, liability and prices soared, and several manufacturers halted production. A vaccine shortage resulted and public health officials became concerned about the return of epidemic disease. To reduce liability and respond to public health concerns, Congress passed the National Childhood Vaccine Injury Act (NCVIA) in 1986.