Now that COVID-19 surge testing on Oahu is finished after a nearly three-week run, one key metric to monitoring the severity of the pandemic in Hawaii might get worse.

Hawaii’s rate of tests that are positive for the virus has been depressed by the flurry of free tests made available to Oahu residents regardless of whether they had symptoms or suspected connections to known cases.

The statewide positivity rate had been alarmingly high — above 5% — for most of August.

But because of 60,274 tests given through the surge testing program, the statewide seven-day-average positivity rate has been below 5% since Aug. 29 — three days after surge testing began through a city, state and federal government partnership.

State health industry officials caution that the recent reduction in Hawaii’s positivity rate should not be misunderstood, even though the number of new daily coronavirus cases has come down significantly over the past week or so.

Data from the state Department of Health put Hawaii’s COVID-19 average positivity rate at 2.2% over seven days through Monday. But if you exclude the 0.6% positive case rate from about 20,000 surge tests in the same time frame, the overall positivity rate is 3.6%.

Some local health care industry executives think the positivity rate excluding surge tests is actually over 5%.

Mark Mugiishi, president and CEO of the Hawaii Medical Service Association, said his own rough calculation puts Hawaii’s positivity rate at about 6%.

“We’re reporting all tests, and that includes surge testing, which as you know increases the denominator a lot,” Mugiishi said Monday during a meeting of a special state House committee focused on COVID-19.

The president and CEO of Hawaii Pacific Health, Ray Vara, who like Mugiishi is a member of the committee, said he also thinks Hawaii’s COVID-19 positivity rate is about 6% if all surge testing data is removed.

On some days of Oahu’s surge testing, there were more surge tests than nonsurge tests done in Hawaii. Health Department officials have yet to receive and tally results from close to 15,000 surge tests.

According to archived data at covidpau.org, Hawaii’s COVID-19 positivity rate over seven-day rolling averages was 2% or less this year through late July before jumping to 6% during most of August.

The higher positivity rate in August coincided with a spike in new cases that frequently topped 200 or 300 a day.

Then over the last couple of weeks or so, the positivity rate was dampened in part from results of the surge testing program rolled out in response to high case counts.

Honolulu Mayor Kirk Caldwell set a goal to test 60,000 people over 14 days, but based on demand, the city received from the federal government another roughly 30,000 tests that Caldwell plans to use strategically through November.

According to a Johns Hopkins Bloomberg School of Public Health article published Aug. 10, the positivity rate is useful to understand whether sufficient COVID-19 testing is being done and whether appropriate restrictions on people gathering are in place.

The article said one “rule of thumb” threshold is that a 5% positivity rate is too high.

In May the World Health Organization said in a report that one factor suggesting that COVID-19 has been controlled is a positivity rate under 5% for at least two weeks.