The U.S. Centers for Disease Control and Prevention on Thursday bumped Honolulu and Maui counties from the yellow, medium-risk community level to the red, high-risk community level for COVID-19.

Honolulu and Maui counties join Kauai County, which last week was classified as a high-risk community due to high case rates and limited hospital capacity. Hawaii County remains yellow.

Under CDC guidelines those living in high-risk communities should wear a well-fitting mask in public indoors and on public transportation, regardless of vaccination status.

None of the county mayors, however, planned to immediately reinstate an indoor mask mandate.

CDC said people should also stay up to date with their COVID-19 vaccines and get tested if they have symptoms. Those who are immunocompromised or at high risk for severe disease should take additional precautions.

Three metrics are used to determine community levels: new COVID-19 admission rates at hospitals, percentage of hospital beds used by COVID-19 patients, and coronavirus case rates per 100,000 people.

In Honolulu County, CDC counted about 505 cases per 100,000 people, 12.4 new COVID-19 admissions per 100,000 and 4% of staffed inpatient beds used by patients confirmed to have COVID-19.

In Maui County, CDC said, there were about 472 cases per 100,000 people, 12.4 new COVID-19 admissions per 100,000 and 4% of staffed inpatient beds used by patients confirmed to have COVID-19.

In Kauai County, rates were even higher. CDC listed about 636 cases per 100,000 people, 9.7 new COVID-19 admissions per 100,000 and 10.2% of staffed inpatient beds used by patients confirmed with COVID-19.

Kauai Mayor Derek Kawa­kami noted the red status in a county briefing Thursday and said masks should be worn indoors in public places.

“Again, use your best judgment when it comes to the safety of yourself and your family members,” he said.

He offered condolences to the family of the county’s latest COVID-19-related death, a male resident in his 90s who was hospitalized.

The Kauai Health District Office is investigating more than a dozen active clusters, he said, mostly at workplaces, and started by an employee who went to work while sick.

Maui Mayor Mike Victorino said the high rate of COVID- 19 transmission in his county is a concern but not unexpected given the elimination of public-health mandates throughout Hawaii.

He said Maui’s main metric continues to be its health care capacity, and that the county was doing fine in that regard.

On Thursday he said Maui Memorial Hospital had 13 patients with COVID-19, with one in intensive care, and none on ventilators.

“I urge everyone to follow CDC guidance for high risk communities,” said Victorino in a statement. “Wear masks indoors when in public places and on public transportation. If testing positive with a home COVID-19 test kit, get a confirmatory test and report results to the Hawaii DOH. Stay home and isolate if not feeling well and maintain physical distance. We’ve been through previous surges and we will get through this one too.”

Honolulu Mayor Rick Blangiardi, in the Honolulu Star-Advertiser’s Wednesday “Spotlight Hawaii” livestream program, encouraged people to wear their masks and to get boosted, if eligible. He said a mask mandate was a “possibility” if hospitals got crowded but that the county was not mandating masks at this point.

“With coronavirus case counts rising on Oahu once more, I am encouraging everyone to continue to demonstrate personal responsibility by wearing masks and getting their vaccine and booster shots,” he said in a statement. “My administration is not actively considering the reinstatement of any coronavirus restrictions at this time, including mask mandates, but we will always work with our partners in the health care industry to consider all possible solutions to any situation that warrants a response.”

The latter part of the statement was shared in a tweet Wednesday evening. On Thursday the mayor’s office said he stood by those statements.

On Wednesday the state Health Department reported Hawaii’s seven-day average of new cases at 925, representing the eighth consecutive weekly increase.

The average positivity rate for Kauai rose to 23.0% Wednesday, according to DOH, while those for Honolulu and Maui counties increased to 18.5% and 16.2%, respectively.

Currently, about one-third of the U.S. population lives in higher-risk areas with rising coronavirus cases and hospitalizations, according to federal officials, and should consider masking indoors.

The community levels are updated by CDC every Thursday.