US President Donald Trump and Dr Anthony Fauci are at odds over the use of hydroxychloroquine as a COVID-19 treatment.
At least nine US states have reported record increases in COVID-19 cases during the last seven days, mostly in the upper Midwest and West where colder weather is forcing people indoors.
Health experts have long warned that colder temperatures driving people inside could promote the spread of the virus. Daytime highs in the upper Midwest are now in the 10s Celsius (50s Fahrenheit).
Four states – Kentucky, Minnesota, Montana and Wisconsin – saw record increases in new cases, according to a Reuters analysis. Kansas, Nebraska, New Hampshire, South Dakota and Wyoming also set new records for cases last week.
The US Centers for Disease Control and Prevention (CDC) on Sunday reported an increase of at least 49,327 cases from its previous count, and said that the number of deaths had risen by at least 703.
While the death rate has gone down by about 12 percent, nearly 210,000 Americans have now died from COVID-19.
According to separate Johns Hopkins University data, only Texas, Missouri and South Carolina have reported a decrease in the number of cases.
New York is one of only 18 states where cases have not risen greatly during the past two weeks, according to a Reuters analysis.
But on Sunday, New York City Mayor Bill de Blasio announced that he is moving to shut non-essential businesses, as well as schools, in nine neighbourhoods, starting on Wednesday. The lockdown would require the governor’s approval.
Meanwhile, Montana has reported record numbers of new cases for three out of the last four days and also has a record number of COVID-19 patients in its hospitals.
Wisconsin has set records for new cases for two of the last three days and also reported record hospitalisations on Saturday. On average 22 percent of tests are coming back positive, one of the highest rates in the country.
Wisconsin’s Democratic governor mandated masks on August 1, but Republican legislators are backing a lawsuit challenging the requirement.
North Dakota, South Dakota and Wisconsin have the highest new cases per capita in the US.
Wisconsin Senator Ron Johnson is one of several prominent Republicans who have tested positive for coronavirus since President Donald Trump announced he had contracted COVID-19.
Because of the surge in cases some nursing homes and assisted-living facilities are barring visitors, while Bellin Health, which runs a hospital in Green Bay, Wisconsin, said last week its emergency department has been past capacity at times and doctors had to place patients in beds in the hallways.
The US is reporting 42,600 new cases and 700 deaths on average each day, compared with 35,000 cases and 800 deaths in mid-September. Deaths are a lagging indicator and tend to rise several weeks after cases increase.
Kentucky is the first Southern state to report a record increase in cases in several weeks. Governor Andy Beshear said last week was the highest number of cases the state has seen since the pandemic started.
State health experts have not pinpointed the reason for the rise but point to fatigue with COVID-19 precautions and students returning to schools and colleges. Across the last two weeks, Kentucky has reported nearly 11,000 new cases and has seen hospitalisations of COVID-19 patients rise by 20 percent.