Coronavirus updates: 84% of California population to go on lockdown Sunday night

CDC Director Robert Redfield said he believes December, January and February will "be the most difficult time in the public health history of this nation."

“December and January and February are going to be rough times," Redfield said at a virtual Chamber of Commerce event. "Largely because of the stress that it’s going to put on our health care system."

Redfield said he anticipates another 150,000 to 200,000 deaths by February. That would bring the COVID-19 death toll to at least 422,000 Americans.

Two residents of the Hawaii island of Kauai were arrested for flying home when they allegedly knew they had tested positive for COVID-19, said Kauai Mayor Derek Kawakami.

They were arrested by Kauai police for "second-degree reckless endangering," Kawakami said.

Kauai has seen an "unprecedented surge" in cases, the mayor said. As of Tuesday, the island had 16 active cases, according to the Health Department.

New York Gov. Andrew Cuomo said he expects the state to receive 170,000 doses of Pfizer's vaccine on Dec. 15 if all safety and efficacy approvals are granted.

Cuomo said he expects additional doses of Pfizer's vaccine as well as initial allocations of Moderna's vaccine, if approved, later this month.

Cuomo says effective widespread immunization could take until June through September.

Meanwhile, Cuomo says New York faces "another mountain" in the fight against rising cases and hospitalizations.

The governor reiterated that small gatherings are the No. 1 cause of COVID-19 spread in the state.

Of the over 193,000 tests reported in New York on Tuesday, 4.63% were positive, Cuomo said.

-ABC News' J. Gabriel Ware

The Centers for Disease Control and Prevention on Wednesday announced alternatives to its two-week recommended quarantine for people who have been exposed to COVID-19.

Quarantine can now end after 10 days without a test if the individual has not reported any symptoms, or after seven days with a negative COVID-19 test and no reported symptoms, said Henry Walke, the CDC's COVID-19 incident manager.

Walke said the move "may make it easier for people to take this critical public health action by reducing the economic hardship associated with a longer period, especially if they cannot work during that time."

People should continue to monitor for symptoms for the full 14 days after being exposed to the virus "especially if quarantine is discontinued early," he said.

A 14-day quarantine remains the best way to prevent spread, according to the CDC.

Walke added, “Everyone should follow this specific guidance from their local public health authorities about how long they should quarantine.”

-ABC News' Sophie Tatum