Health experts at the University of Washington said 70,000 lives could be saved if people were scrupulous about wearing masks.
US infectious disease expert said he "wouldn’t have imagined in my wildest dreams" that people would threaten him over public health principles.
The director of the World Health Organization urged people to practice “the basics of public health" to stop outbreaks of Covid-19.
Frustrated with his low approval ratings, the president is once again leaning in to hydroxychloroquine as a Covid-19 treatment.
"It can only be my personality, that’s all," Trump said at a news conference where he lamented his plunging popularity.
Change of heart follows a weekend of golf and after two Yankees players knelt during the national anthem at a stadium in Washington.
The president also took a jab at Anthony Fauci, calling the country's top infectious disease expert "a little bit of an alarmist."
The ongoing pandemic shows just how dangerous, and deadly, his continued rejection of science and expertise can be.
The daily increase could reach 100,000 unless a nationwide push is made to tamp down the fast-spreading, according to Dr Anthony Fauci.
Across the country, cases of Covid-19 are suddenly surging, particularly in states that had begun to reopen.