The highly contagious omicron subvariant BA.2 now makes up four out of every 10 new coronavirus cases in Hawaii, according to the latest report from the state Department of Health.

The variant report, published Tuesday, found that the estimated proportion of BA.2 grew from 13% just two weeks ago to 40% of variants circulating in the state.

The report also confirmed there were 236 cases of BA.2 detected in samples collected from Jan. 6 to March 19, more than double the 111 confirmed in the mid-March report.

“This is not unexpected,” said Edward Desmond, State Laboratories Division administrator, explaining that BA.2 was expected to double every two weeks or so.

“That’s pretty close to what we’ve been seeing. So it’s 40% now, and theoretically around two weeks from now it will be double that. It spreads more efficiently and more effectively than the original omicron strain, so I expect it will become prevalent within the coming months for sure.”

The BA.2 subvariant, first detected in Hawaii on Jan. 28, is already the dominant strain across the U.S. and world, with the U.S. Centers for Disease Control and Prevention reporting it made up about 55% of new cases in the nation for the week ending Saturday.

The World Health Organization also confirmed it is the dominant strain around the globe, driving recent surges in several European countries, including the United Kingdom, as well as in South Korea and China.

While BA.2 is considered to be more contagious than the original omicron strain, it has not been shown to result in more severe illness and hospitalizations, according to health experts.

Desmond said he does not expect to see an increase in hospitalizations in Hawaii associated with the subvariant.

Hawaii’s statewide average positivity rate, meanwhile, inched up over the past few weeks.

On Wednesday the state Department of Health reported 1,187 more COVID-19 infections statewide compared with the previous week, bringing Hawaii’s total since the start of the pandemic to 240,778 cases. Six more deaths were reported, bringing the state’s COVID-19 death toll to 1,379.

The seven-day average of new cases statewide Wednesday was 129, according to DOH, and the weekly average positivity rate was at 3.3%. That was an uptick from 2.9% last Wednesday and 2.3% the Wednesday before that.

Hospitalizations of patients with COVID-19, meanwhile, plummeted to 16 on Wednesday, with only three in intensive care and two on ventilators.

Approximately 100 remaining traveling nurses of the 680 funded by the Federal Emergency Management Agency who arrived to help during the omicron surge worked their last shifts Wednesday, according to the Healthcare Association of Hawaii.

In a previous variant report, BA.2 was confirmed to be present on Oahu, Maui and Hawaii island due to test sample sequencing, and was independently confirmed on Kauai due to its presence in wastewater sampling conducted for an academic project.

The latest variant report confirms the presence of one case of BA.2 on Kauai via sequencing of test samples from the county.

Other versions of omicron that are present in the isles include the original BA.1 and BA.1.1 detected in South Africa, BA.1.14 detected in Brazil, and BA.1.7 and BA.1.10 detected in the United Kingdom, according to the report.

The Hawaii Pandemic Applied Modeling Work Group, a volunteer group of data scientists, epidemiologists and academics, said in its latest forecast that lifting mitigation measures in all counties is expected to result in a small increase in COVID-19 cases, but not a significant surge.

But the work group said it is important to remain vigilant, as COVID-19 has been underestimated many times.

DOH this week also approved a second booster dose of the Pfizer or Moderna vaccines for those ages 50 and older four months after the first one, as well as for those 12 or older with compromised immune systems, in line with the latest CDC guidance.

Some experts say Hawaii’s vaccination rate, which as of Wednesday was at 77% for the primary series and 38.4% for boosters, paired with immunity from those previously infected, should help prevent the same level of surge as recently seen with the original omicron variant.

Dr. Maria Van Kerkhove, WHO’s COVID-19 technical lead, said COVID vaccines remain effective at preventing severe disease and death against both BA.1 and BA.2.

But strong surveillance, including sequencing, and testing around the world are critical to tracking the virus’s evolution, she said.

The state Health Department, meanwhile, has purchased equipment and set up standard operating procedures for wastewater monitoring in Hawaii, but does not expect to conduct its own testing or have the program running fully until this summer.

A total of 12 wastewater treatment sites in Hawaii so far — on Kauai, Oahu and Hawaii island — are participating in the CDC’s National Wastewater Surveillance System.