Public-health officials in Hawaii are on alert for a new COVID-19 variant that has emerged in California and are urgently advising eligible residents to get vaccinated as soon as possible to avoid serious illness or hospitalization.

Three mutant strains are already circulating in the islands, and one of them — the B.1.429 variant that originated in California — now accounts for 59% of COVID-19 specimens that have undergone genomic sequencing in the Department of Health’s State Laboratories Division, according to data released Friday.

The B.1.1.7 strain from the United Kingdom has a lesser presence in Hawaii, and the B.1.351 strain first found in South Africa is here to an even smaller extent, according to Dr. Edward Desmond, administrator of the State Laboratories Division.

But looming on the horizon to the east of the islands is a “mysterious” new variant recently detected in California, said Desmond in the Health Department’s “The Weekly Dose” video posted Friday on Facebook. The new variant, first found in Mumbai, India, contains mutations of both the California and South African variants, which are known to spread more easily and are less responsive to antibodies from vaccines or previous infection.

Desmond said the full extent of the threat posed by the double-mutant strain isn’t known yet.

“This strain is brand new, it hasn’t been studied,” he said. “I guess the ominous news is that shortly after it was reported in India, it was also reported in California, and I guess we’ve seen that what happens in California comes fairly quickly here, like the California variant B.1.429 has come here. So this is something we’re going to keep an eye on.”

The presence of COVID-19 variants varies from county to county, accounting for about 59% of Oahu cases. On Maui, 82% of cases involve the dominant California variant, a likely explanation for the island’s high infection rates in recent weeks, according to Desmond.

Maui has led the state in per-capita average daily new cases since Dec. 24, with the most recent DOH data showing 13.7 cases per 100,000 residents as of Wednesday. That compares with 5.7 cases per 100,000 for Oahu and the state as a whole.

As of Friday, Maui reported a seven-day average of 23 daily new cases.

The surge in COVID-19 infections coincides with big increases in air arrivals in recent months. On Thursday alone Kahului Airport saw 6,424 arrivals, including 5,244 visitors and 242 returning residents, according to the Hawaii Tourism Authority.

Due to concerns about travelers introducing variant strains to the county, Maui got approval from Gov. David Ige earlier this week to require trans-Pacific passengers to undergo rapid testing for COVID-19 upon arrival, even if they obtain a negative pre-travel test result under the state’s Safe Travels program.

Although variants show resistance to vaccines, health officials say being vaccinated against COVID-19 can reduce transmission and lessen symptoms if infected.

“The good news is even though the antibodies are less effective, people who have been vaccinated or previously infected, they are still not going to get seriously ill,” Desmond said. “So you don’t have to be concerned that vaccination is not going to protect you because of these variants.

“Get vaccinated anyway. You may get a mild case, but the vaccine prevents serious illness and you won’t go to the hospital.”

Another reason to get the shots: Ige’s latest emergency proclamation, issued Friday, establishes an exemption from Safe Travels testing and self-quarantine rules to fully vaccinated travelers. The new exemption will go into effect once set up by the director of the Hawaii Emergency Management Agency, with details to be announced later.

The DOH reported Friday that 906,777 COVID-19 vaccine doses had been administered in Hawaii so far, with 31% of the state’s population receiving at least one shot.

But just as the DOH announced Thursday that vaccination eligibility on Oahu would be expanding to residents age 50 and older starting Monday, the state learned that its weekly allotment of coronavirus vaccine would be greatly reduced next week due to production issues with Johnson & Johnson’s one-dose vaccine.

DOH spokesman Brooks Baehr said Friday that Hawaii received 90,080 doses this week, including 21,300 doses of the Johnson & Johnson vaccine. Next week’s allotment will drop to 76,060 doses, with only 2,600 doses from Johnson & Johnson.

Supplies of the Johnson & Johnson vaccine will be extremely limited nationwide until federal regulators clear production at a Baltimore manufacturing plant with a history of quality control problems, the White House’s pandemic response coordinator said Friday.

Baehr said officials hope the interruption in vaccine supplies will be temporary, but it provides another reason “to sign up now,” and before April 19, when eligibility on Oahu expands to residents age 16 and older. He said to check hawaiicovid19.com to find vaccination opportunities at local pharmacies.

People 16 and older are already eligible for COVID-19 vaccinations in Hawaii, Maui and Kauai counties.

Also Friday, health officials reported 87 new coronavirus infections statewide, bringing the state’s total since the start of the pandemic to 30,571 cases. There were no new coronavirus-related deaths as the statewide death toll remained at 470.

The new cases include 67 on Oahu, 11 on Maui, four on Hawaii island and five Hawaii residents diagnosed outside the state. As a result of updated information, state health officials removed one Oahu case from the counts.

The statistics released reflect the new infection cases reported to the department Wednesday.