Daniela Hernandez

The speedy discovery, announcement and global response shows a new phase in fight against Covid-19, as health officials hunt for variants that could evade vaccines.

Isolation exacerbated the devastation felt by athletes who tested positive for Covid-19 in Tokyo. One athlete built a companion named Bob for company.

Mask-wearing, good air flow and frequent rapid tests are more important than surface cleaning, temperature checks and plexiglass. Scientists say America needs to double down on...