Despite more vaccinations around the world, infectious disease experts are coming to a consensus that COVID, as a viral strain, isn't going anywhere soon. Instead, it's likely to be endemic, meaning the virus will become a constant in our lives like seasonal mutations of the flu. A major factor in how well we control COVID in the years to come will be dependent on herd immunity. What does this mean? Is it even achievable? Dr. David Fisman, an epidemiology professor at University of Toronto's Dalla Lana School of Public Health, explains how the world is "going to have to figure out how to live with an endemic pathogen that's nasty."