On Thursday, the Department of Health released its survey of wastewater, which tests for community levels of COVID-19.

The survey shows that COVID-19 cases have declined since early June and the omicron subvariant BA.5 is by far the dominant strain of COVID-19 in the state. The next highest concentration of a strain is BA.2.12.1, which is followed by BA.2 and BA.4. These are all parent or sublineages of omicron.

The BA.5 subvariant has also been the most dominant strain nationwide since early July. However, there are concerns now about a trio of new omicron subvariants — BF.7, BA.4.6 and BA.2.75 — that are becoming more prevalent in the U.S. 

Hawaii’s wastewater survey is informative since many people are now taking at-home rapid tests instead of taking PCR tests through clinics to determine if they are positive, which decreases the state’s COVID-19 case counts. 

For the week of Sept. 21 to Sept. 28, Hawaii reported 12,755 cases of COVID-19. This number includes reinfections. 

“Data from wastewater testing aligns with other data sets,” said State Laboratories Division Administrator Edward Desmond in a news release.

“Results from COVID-19 tests taken by individuals show case counts have dropped since June. This is consistent with data in the Wastewater Report, which shows concentrations of SARS-CoV-2 have declined since June. Genome sequencing shows BA.5 is the most common subvariant in Hawaii. The Wastewater Report also supports that finding,” Desmond said.

A wastewater survey can also be an early warning for emerging outbreaks because infected people shed up to three days before showing symptoms and because people who are both asymptomatic and symptomatic shed COVID-19 in their feces. 

In order to conduct the survey, the Department of Health coordinated the collection of samples from 15 wastewater treatment plants across the state. The testing is done by Biobot Analytics as part of the National Wastewater Surveillance System. 

The State Laboratories Division will publish a Wastewater Report every two weeks. 

Michelle Broder Van Dyke covers the Hawaiian Islands for Spectrum News Hawaii.