Science's COVID-19 reporting is supported by the Heising-Simons Foundation.
A team of researchers in rural Maharashtra state visits houses to track the spread of COVID-19 in India.
PHOTO: RAJA SENGUPTA
At a tiny rural hospital about 1 hour's drive northeast of Pune, India, in early April, workers loaded an SUV with coolers, syringes, vials, thermometers, and electronic tablets. They drove 20 minutes to the village of Karandi, slowing to pass caravans of migrant sugarcane cutters in ox carts. They spent more than an hour taking blood samples at a cluster of houses shared by three generations of one family. Later, the team would scour the blood for antibodies that indicate past run-ins with COVID-19.