"safer" because of inaction

2) Omission bias. “One interesting bias I've come upon is the omission bias,” says Dr. Nidhi Ghildayal, researcher and PhD in Public Health at the University of Minnesota. In regard to vaccines, the omission bias occurs when “parents believe that the act of vaccinating, which they may have heard has a small chance of [side effects], is worse than simply not committing any action, even if the potential consequences of this non-action pose a significantly higher risk.” In other words, not vaccinating can feel safer because it's an inaction – even though the risks involved in that inaction are greater.

www.forbes.com/sites/sarahwatts/2019/02/21/5-cognitive-biases-that-explain-why-people-still-dont-vaccinate/?sh=37c1edb34414