Online Marketing Tools

Covid World Vaccination Tracker More than 5.55 billion people worldwide have received a dose of a Covid-19 vaccine, equal to about 72.3 percent of the world population. This map shows the stark gap between vaccination programs in different countries.

Illustration: Fran Pulido/The Guardian The idea was simple. Recruit hundreds of people in their 80s and 90s, equip them with fitness trackers, and monitor their physical activity. Then, when the pa…