It’s Hard to See the Peak

Health experts say not to expect a single peak day — when new cases reach their highest level — to determine when the tide has turned. As with any disease, the numbers need to decline for at least a week to discern any real trend. Some health experts say two weeks because that would give a better view of how widely the disease is still spreading. It typically takes people that long to show signs of infection after being exposed to the virus.
But getting a true reading of the number of cases of COVID-19, the disease caused by the coronavirus, is tricky because of the lack of testing in many places, particularly among people under age 65 and those without symptoms.
Another factor is that states and counties will hit peaks at different times based on how quickly they instituted stay-at-home orders or other social distancing rules.
“We are a story of multiple epidemics, and the experience in the Northeast is quite different than on the West Coast,” said Esther Chernak, director of the Center for Public Health Readiness and Communication at Drexel University in Philadelphia.
Also making it hard to determine the peak is the success in some areas of “flattening the curve” of new cases. The widespread efforts at social distancing were designed to help avoid a dramatic spike in the number of people contracting the virus. But that can result instead in a flat rate that may remain high for weeks.
“The flatter the curve, the harder to identify the peak,” said William Miller, a professor of epidemiology at Ohio State University.