No  one could question the positive impact vaccines and the immunization they provide have had on global health. The World Health Organization estimates that immunizations prevent the deaths of between 2-3 million people each year - and could prevent an additional 1.5 million deaths if vaccination efforts were more globally available and accepted. Despite being one of the most cost-effective medical interventions, vaccines are still not universally available, especially in the developing world. And yet, even in those countries where vaccines are readily available, many individuals still choose not to be vaccinated. Who is impacted by this choice?

Since the inception of the Hospital-Acquired Condition Reduction Program (HACRP) in 2015, those of us involved in the world of hospital infection control have become used to looking at HAC scores. For a few years, these hospital scores have been expressed as a number between 1 and 10. Now, HAC scores look different: They can be positive or negative, and only seem to be between -3 and +3. What gives?