Coronavirus updates: 'Close contact' definition updated by CDC

U.S. Surgeon General Jerome Adams said Wednesday that a "herd immunity" approach to combating COVID-19 could "lead to many complications/deaths."

Adams posted the comment on his official Twitter account, along with a link to a recent article from The Journal of the American Medical Association entitled "What is Herd Immunity?"

"The summary: Large numbers of people would need to be infected to achieve herd immunity without a vaccine; this could overwhelm health care systems and lead to many complications/deaths," Adams tweeted. "So far, there is no example of a large-scale successful intentional infection-based herd immunity strategy."

Instead, Adams urged people to "wear masks," "wash hands" and "watch distances."

The surgeon general's comments come after the White House embraced a controversial declaration by a group of scientists calling for an approach that relies on "herd immunity."

The so-called Great Barrington Declaration, which claims on its website to have been signed by more than 9,000 medical and public health scientists around the globe, opposes lockdowns and argues that authorities should allow the novel coronavirus to spread among young, healthy individuals while protecting the elderly and the vulnerable.

Dr. Anthony Fauci, the nation’s top expert on infectious diseases, has called the concept "ridiculous" and "total nonsense."

The Czech Republic confirmed 11,984 new cases of COVID-19 on Tuesday, a new record for the Central European country.

The Czech Republic has shattered its own record already several times this month. The country's previous record of 11,105 new cases was set last Friday.

The cumulative total now stands at 193,946 cases, about one third of which were registered in the past seven days, according to data from the Czech health ministry.

More than 113,000 cases were active, including 4,064 patients who remained hospitalized for COVID-19, while over 79,000 have recovered from the disease, according to the health ministry data.

So far, 1,619 people have died from the disease in the Czech Republic. The country's highest single-day death toll of 97 was recorded on Monday, according to the health ministry data.

The Czech Republic has the highest rate of COVID-19 infection in Europe. Over the past two weeks, the country of 10.7 million people has reported 975.8 cases per 100,000 population, according to data published Wednesday by the European Center for Disease Prevention and Control.

New restrictive measures, including mandatory mask-wearing outdoors and in cars, are slated to take force across the Czech Republic on Wednesday. The government was expected to meet early Wednesday to discuss additional measures.

An ABC News analysis of COVID-19 trends across all 50 U.S. states as well as Washington, D.C. and Puerto Rico found there were increases in hospitalizations over the past two weeks in 42 states.

The analysis also found increases in newly confirmed cases of COVID-19 in 40 states plus Puerto Rico, increases in the daily positivity rate of COVID-19 tests in 27 states and increases in daily COVID-19 death tolls in 17 states.

Since Oct. 1, there have been 972,902 cases reported nationwide. More than 400,000 of those cases have been reported in just the last seven days. The country is on track this week to exceed 1 million cases for the month of October, making it the fourth month on record to surpass the grim milestone.

Cases are undoubtably surging nationally. The United States is currently averaging 57,000 new cases a day -- the highest it has been in 11 weeks. That average has increased by 67% since Sept. 12.

Two states -- Kansas and Tennessee -- hit a record number of new cases reported in a 24-hour reporting period, while five states -- Kentucky, Montana, Nebraska, Ohio and Wyoming -- saw a record number of current hospitalizations in a day.

The trends were all analyzed from data collected and published by the COVID Tracking Project over the past two weeks, using the linear regression trend line of the seven-day moving average to examine whether a state's key indicators were increasing, decreasing or remained flat.

ABC News' Benjamin Bell, Brian Hartman, Soorin Kim and Arielle Mitropolous contributed to this report.

There were 60,315 new cases of COVID-19 identified in the United States on Tuesday, according to a real-time count kept by Johns Hopkins University.

The latest daily tally is up by almost 2,000 from the previous day but remains under the country’s record set on July 16, when there were 77,255 new cases in a 24-hour-reporting period.

An additional 993 coronavirus-related fatalities were also recorded Tuesday, more than double the previous day's death toll but still down from a peak of 2,666 new fatalities reported on April 17.

A total of 8,274,797 people in the United States have been diagnosed with COVID-19 since the pandemic began, and at least 220,133 of them have died, according to Johns Hopkins. The cases include people from all 50 U.S. states, Washington, D.C. and other U.S. territories as well as repatriated citizens.

By May 20, all U.S. states had begun lifting stay-at-home orders and other restrictions put in place to curb the spread of the novel coronavirus. The day-to-day increase in the country's cases then hovered around 20,000 for a couple of weeks before shooting back up and crossing 70,000 for the first time in mid-July. The daily tally of new cases has gradually come down since then but has started to climb again in recent weeks.

The number of new COVID-19 cases recorded in the United States increased by more than 12% in week-over-week comparisons, according to an internal memo from the U.S. Department of Health and Human Services that was obtained by ABC News on Tuesday night.