After six straight weeks of declines in new Covid-19 cases in the US, that number has started to plateau, even as hospitalizations and deaths continue to drop. The 7-day average of daily new cases was just over 72,000 on Wednesday, according to data from Johns Hopkins University, a total that is relatively unchanged from last Thursday. … Experts say it is too soon to tell whether this one-week flattening represents a small blip or the beginning of a broader issue.