The C.D.C. is urging communities to reopen schools as quickly as possible, but parents and teachers have raised questions about the quality of ventilation available in public school classrooms to protect against the coronavirus.
In a city scrambling to vaccinate people against Covid-19 as quickly as possible, Ambar Keluskar faced a problem this month that seemed to defy logic: Mr. Keluskar, a pharmacist in Brooklyn, struggled to find people to take the 200 doses he had on hand.
