Oct. 23 (UPI) -- Updated data Friday shows the United States has added a staggering 71,000 new COVID-19 cases -- the fourth-highest to date and the most in three months.
Research at Johns Hopkins University showed about 71,700 new cases on Thursday. That's the highest one-day figure since July 24 and punctuates what's been a substantial increase in cases nationwide over the past seven weeks.
Johns Hopkins data showed more than 850 new deaths.
Since the start of the pandemic, there have been 8.41 million cases and about 223,100 deaths in the United States. The national daily average has risen 42% over the last two weeks, according to the health news website Stat.
Health experts suspect rising cases are being caused by a combination of people moving indoors due to colder weather, "pandemic fatigue" and college students returning to classes.
"I think it's really a number of factors coming together," Emory University epidemiologist Bob Bednarczyk told USA Today.
"What I worry that they're starting to come together in a perfect storm."
Health officials have warned for weeks that the colder weather and flu season have the potential to make the pandemic worse.
In Idaho, heath officials saw a record number of cases Thursday and the state's positivity rate climbed for a fifth consecutive week.
Republican Gov. Brad Little has declined to mandate face masks or limit crowd sizes beyond requiring distancing at some events and in businesses. Idaho has the nation's fifth-highest rate of transmission, according to the Brown School of Public Health.
In Utah, which has the nation's eighth-highest rate, the state health department reported record cases and hospitalizations Thursday.
"Our cases are at an all-time high. Our hospitalizations are at an all-time high and will continue to rise if this trend in cases continues," infectious disease specialist Dr. Edward Stenehjem told KSL Radio.
"For the first time as a physician, I'm scared to see what's to come," he said. "I'm scared about the next few months that we will endure here in Utah, unless something changes."