Over the last year, one message has been clearly emphasized: trust science. Evidence, and only high-quality evidence, will form the basis for policy. How has this influenced the coronavirus vaccine campaign? On the one hand, there has been strict adherence to scientific rigor when it fits the desired narrative. On the other hand, scientists may differ in how they interpret the science. For example, some insist treatments are only "evidence-based" when they were evaluated in a double-blind randomized clinical trial and applied using protocols that exactly mirror the research studies. Others are willing to accept evidence from modeling exercises based on questionable assumptions. Yet, when advocating for greater acceptance of vaccines, the scientific standard is far from uniform.
When communicating with the public, the same scientists may apply different standards depending on whether study conclusions fit the desired message. Perhaps the best explanation is what psychologists call confirmation bias, which is the tendency to interpret observations or data in a manner consistent with previously established beliefs and values. Thousands of studies conducted over the last 50 years show how confirmation bias clouds conclusions in the sciences, the arts, politics, judicial decisions, finance, and medicine.