Coronavirus updates: 'Close contact' definition updated by CDC

Russia registered a record 317 deaths from COVID-19 in the last 24 hours, according to the country's coronavirus response headquarters.

The previous record of 286 fatalities from COVID-19 in a 24-hour reporting period was set just last week.

An additional 15,700 new cases of COVID-19 were also confirmed nationwide in the past 24 hours, down from a peak of 16,319 the previous day.

Nearly 28% of the new cases -- 4,389 -- and almost 20% of the deaths -- 63 -- were reported in the capital, Moscow.

The cumulative totals now stand at 1,447,335 cases and 24,952 fatalities, according to Russia's coronavirus response headquarters.

Although Russia has been breaking its own records for daily case counts and deaths almost every day since Oct. 9, authorities there are resisting shutting down businesses again. Few measures have been imposed in Moscow, the epicenter of the country's COVID-19 outbreak and recent surge.

The Eastern European country of 145 million people has the fourth-highest tally of COVID-19 cases in the world, behind only the United States, India and Brazil, according to a real-time count kept by Johns Hopkins University.

ABC News' Alina Lobzina contributed to this report.

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.