Deliberately infecting healthy human volunteers with the SARS-CoV-2 virus in order to test the efficacy of potential COVID-19 vaccines is unnecessary, uninformative, and unethical. And it risks ...

The time frame of a species’ origins provides context for evolutionary questions. However, dates from fossils are often inconsistent with estimates from genetic data. Emerging evidence points to ...

F or the first time since the Centers for Disease Control and Prevention introduced its three-level risk system in March 2022, on June 30 its community level map of Covid-19 cases had the dubious ...