Omicron subvariant BA.5 — perhaps the most transmissible coronavirus variant yet — is gaining a foothold in Hawaii as it dominates the COVID-19 landscape in the rest of the United States.

Omicron subvariants BA.4 and BA.5 together now make up 47%, or nearly half, of the COVID-19 variants circulating in Hawaii, according to the state Department of Health’s latest variant report.

The report, released late Wednesday by the DOH State Laboratories Division, found via genome sequencing that subvariant BA.5 represented 39% while BA.4 represented 8% of test specimens collected in the two-week period ending July 2.

Omicron subvariant BA.2.12.1, meanwhile, made up 42% of variants circulating in the state, down from 58% two weeks prior. BA.2 now makes up just 11% of variants circulating in the state.

Since there is a lag between when sequencing results are processed and tallied for the report, the numbers are likely higher by the time of publication.

Wastewater data can also provide clues to levels of the virus that causes COVID-19 and variants present in a community.

The Centers for Disease Control and Prevention has contracted Biobot Analytics to help collect wastewater data to track virus levels at sites across the U.S., including 14 in Hawaii. Some preliminary wastewater data for several sites across the isles appear to be in an upward trend, though data collection began only recently.

Only Kauai County has elected to allow Biobot to post detailed results on its online platform. Sequencing of Kauai’s wastewater samples shows about 61.3% of samples there are BA.5, while about 7.6% are BA.4 and 31% are in the BA.2 family.

DOH’s own wastewater program, slated to begin this summer, is not operational yet.

While all of the omicron subvariants are considered variants of concern, both BA.4 and BA.5 have an increased ability to evade antibodies elicited by vaccination or prior infection, compared with BA.2.

BA.5, however, appears to have a significant growth advantage over BA.4 despite sharing identical mutations in the spike protein, the report said.

Epidemiologists are most concerned about BA.5, which has swiftly become the dominant lineage nationally, making up about 78% of new COVID-19 cases in the U.S., according to CDC.

Dr. Eric Topol, professor of molecular medicine at Scripps Research, has dubbed BA.5 “the worst version of the virus that we’ve seen” due to its immune escape — or ability to escape antibodies elicited by prior infections and vaccinations.

Dr. Dean Blumberg, chief of the Pediatric Infectious Diseases Division at UC Davis Children’s Hospital, said BA.5 also results in increased viral replication, meaning those infected tend to have the virus longer and shed it longer.

In general, most breakthrough infections have not been severe enough to result in hospitalizations. But Blumberg said there’s emerging evidence that with every COVID-19 infection, risks of long-term effects, including strokes, heart and kidney diseases and other health problems, increase, even if one is vaccinated.

“COVID is not over, and people need to continue to protect themselves,” he said in a recent UC Davis Health video. “Even if people are vaccinated, even if people have had some immunity from infections previously with other strains, you can still get breakthrough infection.”

He encouraged people to be fully up to date on COVID-19 vaccines and to continue masking indoors around others outside of their household.

BA.5 is believed to be driving cases up again in nearly every state on the mainland, from California to New York.

On Wednesday, DOH reported a reversal in trends after several consecutive weeks of declining COVID-19 cases — with an increase in the seven-day average of new cases in Hawaii to 574 and of the state’s average positivity rate to 15.1%.

The State Laboratories Division has so far detected 67 cases of BA.4 and its sublineages, and more than 250 cases of BA.5 and its sublineages in Hawaii in COVID-19-confirmed PCR test samples collected between May and July.

All four major counties of Hawaii — Kauai, Honolulu, Maui and Hawaii — have both BA.4 and BA.5 present in their communities.