With the rollout of vaccines earlier this year, the concept of “herd immunity”—the idea that enough people would become immune to COVID-19 that we could more or less “return to normal”—seemed plausible. But a number of factors are complicating the US’s fight against the pandemic and we’re still seeing thousands of people dying every day. Epidemiologists Amber D’Souza and David Dowdy return to the podcast to talk with Stephanie Desmon about vaccinations and the delta variant, what the future might look like and why we may need to accept that COVID-19 is here to stay.