Public health officials can use rapid sentinel surveillance to measure the spread of COVID-19 in their communities and guide appropriate strategies to limit it, according to a study published late last week in the US Centers for Disease Control and Prevention's (CDC's) Morbidity and Mortality Weekly Report (MMWR).Also, a study published the same day in The Lancet Public Health suggests that healthcare worker absenteeism due to school closures during a pandemic could lead to more deaths than they prevent.Convenience sampling detects virus in patients with no known riskIn the MMWR study, researchers analyzed data from coronavirus sentinel surveillance at four urgent care centers in Santa Clara County, California, from Mar 5 to 14.Guidance at