Some people don't get COVID despite being exposed to the virus — a mystery researchers are trying to unravel.
Why it matters: Understanding the small cohort of "never COVID" people could lead to new vaccine targets or other protections as the world enters the third year of the pandemic.
Human heart cells make a new robotic "fish" swim, scientists reported this week.
Why it matters: The engineering feat is a step toward creating artificial muscle that could one day be used in medicine and in soft robots. In the nearer term, the researchers say the robotic fish offers a platform for studying how heart muscle works in humans.
