The Hawaii Department of Health’s long-awaited COVID-19 wastewater monitoring program is still a work in progress nearly halfway through the summer as the department deals with staffing challenges.

Health Department officials said regular testing is underway at wastewater treatment sites statewide as part of a federal program, but that its own testing program is not fully operational. The department had previously said its own wastewater monitoring program would be operational some time this summer, with no specific date.

“We’re almost halfway through summer and while we have experienced challenges, our wastewater surveillance program continues to progress,” DOH officials said in a statement. Some reasons contributing to the delay were the unexpected loss of two key members of the State Laboratories Division. Two new staffers are expected to begin working later this month, officials said.

The DOH said 15 wastewater treatment facilities on Kauai, Oahu, Maui and Hawaii island have been enrolled in the U.S. Centers for Disease Control and Prevention’s National Wastewater Surveillance System program.

DOH’s State Laboratories Division coordinated the collection of samples from these 15 facilities by Biobot Analytics, which became the CDC’s contractor in May. Additionally, DOH said it reviews the test results.

The value of wastewater monitoring as an early detection system for COVID-19 levels in a community continues to grow as officially reported coronavirus cases become less reliable due to an influx of uncounted home test kit results.

The CDC launched the surveillance system program in September 2020, noting that people who are infected still shed viral RNA in their feces, regardless of whether they have symptoms or not. The data can also capture those who tested positive at home.

Additionally, sequencing of wastewater samples offers information on what variants are circulating in the community, such as BA.5, which is more immune evasive and transmissible than BA.2, and which is currently dominant nationwide.

On Wednesday the DOH reported a weekly average of 528 new cases a day compared with 573 reported July 27. Health officials have estimated actual numbers are at least five to six times higher due to unreported home test kit results.

The state’s average positivity rate also declined to 13.8% compared with 15.7% reported the previous week.

There were 147 patients with COVID-19 in Hawaii hospitals Wednesday, according to the Hawaii Emergency Management Agency’s dashboard, with 19 in intensive care and four on ventilators.

The Healthcare Association of Hawaii, which will provide hospitalization numbers moving forward, reported a seven-day average of 135 COVID-19 patients in hospitals, lower than the previous week, and average of 23 new COVID-19 admissions per day.

The DOH also reported 21 more deaths, bringing the state’s coronavirus-related death toll to 1,592.

Wastewater trends

The CDC in May selected Biobot Analytics of Cambridge, Mass., to work with public health departments across the U.S. to track levels of the coronavirus in wastewater. Biobot is collecting and analyzing wastewater samples from 500 communities across the U.S., including Hawaii, over the next year.

The results are available on CDC’s wastewater metric map which, as of Wednesday, only displayed 12 dots denoting wastewater treatment plants in Hawaii.

On Oahu, the most populated island, there are five dots. One of them is “sewershed 790” in Honolulu, which represents a population of 700,000, but only has data dating back to early June.

A graph representing virus concentration in wastewater over time for sewershed 790 shows concentration starting at a high level in June, then sloping down through that month. In July the concentration level increased, peaking in midmonth and followed by a current downward slope.

Maui County has three wastewater site dots on the CDC map, while Hawaii County has two — one of which has data dating back to June 12, while the other has no data. Kauai County has two sites with sampling that began in late May.

Biobot also displays data on its own website at biobot.io/data, as long as permission is granted by the treatment plant. So far only a Kauai plant has granted permission. Biobot’s dashboard shows that Kauai County’s coronavirus levels in wastewater have been up and down for the past six months. It also shows BA.5 makes up about 90%, while BA.4 makes up about 10%, of wastewater samples on Kauai.

The testing of wastewater samples has proven to be a useful indicator in several other U.S. states and counties for the levels of the SARS-CoV-2, the virus that causes COVID-19, in a community. Some are able to track the levels of COVID-19 case counts against wastewater virus levels, and determine whether they correlate.

Los Angeles County’s Department of Public Health noted that monitoring coronavirus loads in several wastewater samples was critical to helping foreshadow sustained increases or decreases in transmission. It could also serve as “a leading indicator that precedes trends in confirmed cases and hospitalizations.”

In late July, Barbara Ferrer, the county’s director of public health, said wastewater data, which correlated closely with daily case counts during the winter omicron surge, began to show more divergence during the surges in May and June.

“Based on the prior close correlation and the trends, this discordance supports the reality that recent reported case counts are likely underestimating the true magnitude of community transmission,” she said during a media briefing last week. “This likely reflects both reduced PCR (polymerase chain reaction) testing and the greater use and reliance on over-the-counter tests, which as we all know are not reported to the Public Heath Department.”

Wastewater surveillance can identify the presence of the coronavirus shed by both symptomatic and asymptomatic people, the department noted, as well as increases across large geographic areas.

States such as California, Colorado and Missouri have created their own online dashboards to display wastewater COVID-19 data, searchable by specific county sewersheds. In Missouri the public health department partnered with the University of Missouri in 2020 and has one of the most robust sewershed surveillance programs in the U.S., with more than 100 sites. The trends are displayed on a state map, and specific locations can be selected to view trendings on a graph.

Tim Brown, an infectious disease modeler at East-West Center, said any additional data, particularly wastewater COVID-19 data, would be helpful in efforts to pinpoint where Hawaii is in the pandemic.

The weekly COVID-19 case counts are becoming less reliable as more people shift to home test kits, he said, adding that wastewater would serve as a better proxy because the results should be the same regardless of whether people are getting PCR tested or using home test kits.

While the CDC’s online presentation of wastewater data is not useful or understandable to most people, Brown said, by contrast, Biobot presents an easy-to-understand graph plotting of clinical cases per 100,000 against virus levels in wastewater. At the bottom of the graphing, Biobot notes the percentage of COVID-19 variants detected in the wastewater.

In addition to DOH data, Brown looks at Biobot’s Kauai wastewater data and Walgreen’s COVID-19 index, which offers a recent snapshot of its total positive tests and variants in the state.

“Wastewater data tells us that COVID is still widespread in our islands,” Brown said.

The DOH’s biweekly variant report — showing the results of genome sequencing from positive COVID-19 test samples statewide — offers information that is outdated by the time it’s published, making it hard for the public to interpret what is going on, he said.

“We find out what was happening a month ago,” Brown said. “It’s too late.”

DOH officials said when the department’s COVID-19 wastewater program is fully operational, it will likely offer wastewater data in a biweekly report, and intends to make it available to the public online.