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

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

In this week's briefing for governors, the White House Coronavirus Task Force urged all Americans over the age of 65 or with significant health conditions to avoid "any indoor public spaces where anyone is unmasked.”

The briefing said those under 40 years old who saw anyone outside their household for Thanksgiving should assume they're infected and must isolate.

“The COVID risk to all Americans is at a historic high," according to the briefing, which was obtained by ABC News. "The national daily COVID incidence after Memorial Day, but before the summer surge, was fewer than 25,000 new cases/day and is now more than 180,000 new cases/day; COVID inpatients then were fewer than 30,000 but are now more than 90,000; fatalities have more than doubled."

"We are in a very dangerous place due to the current, extremely high COVID baseline and limited hospital capacity; a further post-Thanksgiving surge will compromise COVID patient care, as well as medical care overall," the briefing said.

-ABC News' Josh Margolin and Brian Hartman