The Delta variant of the coronavirus is making infected people sicker more quickly than other strains, Chinese doctors say. Roughly 12 percent of infected people became severely ill, compared with 2 to 3 percent with previous iterations of COVID-19, and 80 percent of symptomatic people developed fevers. Concentrations of the virus in the bodies of those who are infected also reach higher levels and decline more slowly than in other patients. The variant, first identified in India, has spread throughout the United Kingdom is currently rapidly infecting people in Southeastern China. The World Health Organization has called the strain “a variant of concern.”