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

The head of the American Medical Association released a statement following President Trump's tweet that Americans have nothing to fear from the coronavirus.

AMA President Susan R. Bailey noted that in addition to more than 200,000 deaths in the U.S., the virus has caused suffering and long-term problems for many of the 7 million who have contracted it.

"We know vigilance is the best response to the COVID-19 pandemic because this virus doesn't feed on fear; it feeds on complacency," she said in a statement.

Bailey urged Americans to wear masks, wash their hands and social distance.

"We can’t lose sight of our country’s founding motto: E pluribus unum -- out of many, one – and resolve to defeat this virus together," she said.

-ABC News' Victoria Moll-Ramírez

The U.S. death toll from COVID-19 has now surpassed 210,000, according to data compiled by the Center for Systems Science and Engineering at Johns Hopkins University.

The death toll reached 200,000 on Sept. 22 and continues to climb as several locations around the country see rises in cases.

The U.S. leads the world in COVID-19 deaths, followed by Brazil, which has over 146,000 and counting, and India, which has over 102,000 and counting.

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.