An alarming spike in the daily coronavirus case count in Hawaii to 243 on Thursday was driven by the highly transmissible delta variant as well community spread mostly by unvaccinated individuals, health officials said.

Lt. Gov. Josh Green said the jump reflects a surge from Fourth of July gatherings among the unvaccinated as well as community-related exposure.

Approximately 78% of cases in July are from community spread, 20% from Hawaii residents returning from travel and 2% from nonresident travel, he said in an Instagram post.

“I’d make two recommendations to everyone,” Green said. “Have a quiet two weeks. Don’t have significant gatherings, especially if you’re not vaccinated. Just keep it mellow for two weeks, and definitely wear a mask if unvaccinated. And go get vaccinated. If you’re not vaccinated, don’t wait until fall, don’t wait until Christmas. The time to go is now because the delta is super contagious.”

He pointed out that the seven-day average of new cases increased Tuesday to 135, a 185% jump from where it was July 7, according to the Hawaii COVID-19 Data dashboard.

Since the start of the pandemic, Hawaii has recorded 39,892 coronavirus infections. Thursday’s total of 243 new cases is the highest single-day count since early January. They include 146 on Oahu, 50 on Hawaii island, 14 on Maui, eight on Kauai and 25 residents diagnosed while out of state.

Approximately 27% of the new cases involved people ages 18 and younger, according to Department of Health spokesman Brooks Baehr.

“What we are seeing is widespread community transmission around the state,” Baehr said. “We do occasionally see that vaccinated people get infected, but overwhelmingly, the number of new cases we’re seeing are among unvaccinated people.”

As of Thursday, DOH reported 59.5% of Hawaii’s population was fully vaccinated, while 66% had received at least one dose.

The department also reported three new coronavirus-related deaths, bringing the totals since the start of the pandemic to 527 fatalities.

The latest deaths were an Oahu man in his 50s, an Oahu woman in her 60s and a Maui woman in her 60s. All three had underlying health conditions when they were hospitalized with COVID-19.

Officials said the Oahu woman was fully vaccinated — the second fully vaccinated person in the state to have died from the virus.

Health officials had warned that the highly transmissible delta variant would continue spreading, and that has proved to be the case.

What started out as just one case of the delta variant — detected in June in a fully vaccinated Oahu resident who had traveled to Nevada in May — has now grown to 126 cases, according to the latest report from the DOH’s Laboratories Division.

Health officials say it is now the predominant variant of concern in Hawaii, representing 55% of the variants circulating in the state. Delta has been detected in all four major counties since mid-July and is growing most rapidly in Honolulu County, which had 61 cases detected.

Laboratories Division Administrator Edward Desmond said the trend was “more or less what was anticipated” and can be expected to continue. In the previous report July 12, 57 delta-variant cases had been detected, representing about 17% of the variants circulating in the state.

“When this variant is present in a population, it expands,” he said. “It’s more transmissible than the other variants.”

The DOH cluster report released Thursday noted the spread of COVID-19 in the community was “almost entirely among unvaccinated residents.” The report said the spread — exacerbated by the delta variant — was due to travel, Fourth of July gatherings and the relaxation of indoor masking and gathering-size rules.

Health officials are investigating 16 clusters traced to bars, restaurants, social gatherings and places of worship in all four major counties. Nine of the clusters are on Oahu.

The common elements among the clusters, said Dr. Janet Berreman, Kauai Health District officer, include unvaccinated people gathering in indoor settings in close proximity to one another for a prolonged time, with inconsistent mask use.

“I think the most important message in the cluster report is that the disease is not contained to a particular type of setting or a particular geographic location in our state,” Berreman said. “We’re seeing widespread community transmission, and associated with that, we are seeing clusters that are widely distributed, also.”

The good news, she said, is that Hawaii’s available COVID-19 vaccines are “highly effective” in preventing severe disease, hospitalization and death.

“So the most important bottom line is that everyone who hasn’t already been vaccinated should be, and should do so as soon as possible,” Berreman said. “The situation is really urgent with the rapid increase in cases and rapid spread of the delta variant.”

CORONAVIRUS CLUSTERS ACROSS THE STATE

Health officials are investigating 16 clusters across all four major counties:

>> Oahu: Officials are investigating one cluster at a bar and nightclub with 31 cases, two clusters at restaurants with 14 cases, one cluster at an occupational setting with six cases, one cluster at a social gathering with 10 cases and four clusters in the “other” category resulting in 39 cases.

>> Maui County: Officials are investigating a cluster at a social gathering resulting in eight cases.

>> Hawaii County: Officials are investigating a cluster at a correctional facility that resulted in 286 cases and a cluster at a place of worship that resulted in 20 cases.

>> Kauai County: Officials are investigating an educational setting cluster with four cases, a shelter cluster that resulted in seven cases, a social gathering cluster with four cases and a place-of-worship cluster with seven cases.