Covid-19 cases have declined since early June, while the highly contagious omicron subvariant BA.5 remains dominant in Hawaii, according to a wastewater report released Tuesday.

The findings came after the state launched a program earlier this year to test sewage in an effort to help monitor the spread of the coronavirus, surges in the community and new variants.

Health officials say this is another way to track the virus since many people who contract Covid-19 but have mild symptoms or are asymptomatic are less likely to report their cases whereas the virus sheds into the wastewater regardless of the degree of severity.

“Data from wastewater testing aligns with other data sets,” State Laboratories Division Administrator Edward Desmond said in a news release. “Results from Covid-19 tests taken by individuals showcase counts have dropped since June.”

“Genome sequencing shows BA.5 is the most common subvariant in Hawaii. The Wastewater Report also supports that finding,” he added.

The wastewater report is a collaboration with the National Wastewater Surveillance System. According to the report, the Department of Health sampled 15 wastewater treatment plants that serve more than 1.3 million people in the state between June 1 and Sept. 19.

The samples are examined by Biobot Analytics, a wastewater epidemiology company, which sends the report back to the state.

Desmond said at a news conference that the state will be “acquiring a commercially available kit to detect the monkeypox virus in wastewater sometime in the near future.”

The wastewater report will be posted every two weeks on the DOH’s Covid-19 data website.

The data has limits that cannot precisely predict case counts and capture low levels of infection rates in a community. The data may leave out some communities and facilities because they’re not connected to a wastewater treatment plant.

“The State Laboratories Division continues to develop its own Covid-19 wastewater surveillance capabilities,” Desmond said. “Our staff is performing longitudinal validation of our own protocols by comparing results of our wastewater analysis with results of Biobot’s analysis. The fast, cost-free analysis provided by Biobot gives us desired information and affords our staff time to work toward wastewater testing for other pathogens.”