Coronavirus updates: Virus can linger in air for hours, CDC says

After a back and forth last month, the U.S. Centers for Disease Control posted new guidance Monday on its website once again warning people about airborne spread of the coronavirus.

The updated guidelines state some infections can be spread by exposure to the virus in small droplets and particles that can linger in the air for minutes to hours.

The CDC added that those transmissions can take place, "within enclosed spaces that had inadequate ventilation. Sometimes the infected person was breathing heavily, for example while singing or exercising."

"Today’s update acknowledges the existence of some published reports showing limited, uncommon circumstances where people with COVID-19 infected others who were more than 6 feet away or shortly after the COVID-19-positive person left an area," the agency said in a statement.

The updated language does not change CDC recommendations on social distancing, mask wearing, avoiding large gatherings, and conducting any event or gathering outside as much as possible.

The new guidance came a month after the agency was criticized for posting guidance on airborne transmission on its site and then removing it two days later.

John Brooks, the chief medical officer for CDC’s COVID-19 response, apologized for the changes during a Sept. 21 briefing and told reporters that the initial posting went up too early since they were still conducting a scientific review.

-ABC News' Stephanie Epps

All New York City public schools located in the nine ZIP codes that have been deemed hot spots for rising COVID-19 cases will be closed, New York Gov. Andrew Cuomo announced on Monday.

The nine zip codes, located in Brooklyn and Queens, have seen a recent rise in positive tests -- about 100 public schools will be affected.

Mayor Bill de Blasio sent a proposal on Sunday to the state government requesting the closure of all schools and nonessential businesses in those ZIP codes. Cuomo approved the proposal on Monday.

The schools will be closed beginning Tuesday.

There were 12,594 new cases of COVID-19 and 19 fatalities confirmed in the United Kingdom over the past 24 hours.

The latest daily tally is just short of the records set over the weekend when Public Health England said 15,841 cases between Sept. 25 and Oct. 2 were not included in the United Kingdom's reported daily case counts due to a technical issue. The unreported cases were added retroactively to reach Saturday's count of 12,872 new case and Sunday's 22,961.

The cumulative total is now at 515,571 cases with 42,369 deaths, according to the latest data from the U.K. government.

ABC News' Joseph Simonetti and Christine Theodorou contributed to this report.

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 newly confirmed cases over the past two weeks in 33 states plus Puerto Rico.

The seven-day average of new cases in the United States is now the highest it has been since Aug. 22, a concerning national trend as health experts warn that colder temperatures could only exacerbate the spread of the virus.

The analysis also found increases in the daily positivity rate of COVID-19 tests in 25 states, increases in COVID-19 hospitalizations in 35 states plus Washington, D.C., and increases in daily COVID-19 death tolls in 18 states.

Four states -- Nebraska, Montana, South Dakota and Wisconsin -- hit a record number of current COVID-19 hospitalizations in a day. Nine states -- all in the Midwest and West -- have reported a record rise in COVID-19 cases during the last seven days.

Since Sept. 13, the seven-day national average of new cases has increased by nearly 25%.

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.

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