It feels like a cure for this pandemic may be in sight. But for many people, injecting a brand-new scientific discovery into their body won't sit well. So, how are scientists making sure that a COVID-19 vaccine won't cause more damage than the disease? How do regulators decide what an acceptable side effect is? And what would happen if someone did have a serious reaction to the COVID vaccine after it was released? This week, we're devoting our whole show to vaccine safety.