In the fifth summer of Covid, cases are surging, and the Centers for Disease Control and Prevention has reported “high” or “very high” levels of the virus in wastewater in almost every state. The rate of hospitalizations with Covid is nearly twice what it was at this time last summer, and deaths — despite being down almost 75 percent from what they were at the worst of the pandemic — are still double what they were this spring. As children return to schools and Labor Day weekend travel swells, the potential for further spread abounds. Above: A crowded restaurant in Manhattan in June.