In New York City, a study by the Centers for Disease Control and Prevention found the death rate in recent weeks spiked to more than 24,000 deaths above normal — suggesting there were about 5,000 more deaths due to COVID-19 than the city has officially reported.

Meanwhile, the urgent care chain CityMD says it mistakenly told 15,000 people in New York and New Jersey who tested positive for coronavirus antibodies that they’re immune to COVID-19. Medical researchers say they still haven’t established whether people with antibodies are protected from another infection, whether they could still infect other people or for how long any immunity might last. There are also concerns about the reliability of newly developed antibody tests, many of which have been linked to false positives and false negatives.