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Along with an increase in coronavirus cases and hospitalizations, Ventura County’s positive test rate also has climbed in recent weeks.

As the number of people getting tested has spiked, the number of positive cases has also shot up. While officials say that’s to be expected, the rate those tests come back positive for coronavirus also is rising, according to an analysis of county data. 

“We are seeing an increasing percent positivity rate, which is obviously not what we would like to be seeing,” said Erin Slack, an epidemiologist with Ventura County Public Health.

A higher percentage means more disease transmission or more COVID-19 circulating in the community. Called a positivity rate, it is also one of the factors the state looks at when determining whether a county can accelerate reopening.

Ventura County landed on a state watch listas the number of people hospitalized with coronavirus rose – one of the other indicators the California Department of Public Health uses to monitor efforts to contain the virus.

A few days ago, the county also inched over an additional threshold – one measuring elevated disease transmission.

A county is flagged for elevated disease transmission if the 14-day case rate, which measures the number of cases diagnosed divided by the number of people living in the county, exceeds 100 or when its seven-day positivity rate exceeds 8%. 

Infections rise statewide

For each, the higher the number, the more a county is impacted by COVID-19.

The county’s 14-day case rate had increased to 114.7 earlier this week but so far has stayed under the 8% positivity rate set by the state. It’s also lower than some other counties already exceeding the 8% mark, including Imperial, which the state says had a 21.7% positivity rate earlier this week.

But it has climbed. From June 16-22, the rate hit 6.4%, the most recent seven-day rate available because of a lag in test results.

That’s the first time the rate hit 6% since early to mid-April and up from 4.3% a week ago.

In early May, when the county submitted its application to speed up reopening, its positivity rate was 3.5%.

“It is increasing, so it is a concern,” said Public Health Director Rigo Vargas. “We do track it for that reason.”

The same trend has happened statewide.

Gov. Gavin Newsom reported California’s positivity rate at 6% over the last 14 days, up from 4.6% two weeks ago.

“That’s a very high increase. It may not seem like much to some, but every decimal point is profoundly impactful,” said Newsom at a Wednesday briefing.

The statewide seven-day positivity rate was 6.4%, he said.

Coronavirus update Tuesday: 81 more farmworkers positive, pushing county toward 3,000 cases

Hundreds of new cases

The state allows for a seven-day lag time for counties reporting those positivity rates because of delays in getting test results. 

In Ventura County, hundreds of people are getting tested daily. Most days in recent weeks local numbers have exceeded the 1,300 mark, a goal set for the county. On several days, more than 2,000 people were tested, records show.

How long it takes those results to show up in an electronic reporting system depends on the lab and its capacity. 

Statewide, officials hope counties would have most of the results within a week, which is why they set a seve-day lag. In Ventura County, officials said the average is roughly four days, Slack said.

But that doesn’t always happen. On Tuesday, public health got a case with a lab collection date of June 4, she said.

Because of the variability, officials say, it’s difficult to predict whether the positivity rate continued to climb in recent days or leveled off. But plans called for the county to start posting those rates at vcemergency.com.

Cheri Carlson covers the environment for the Ventura County Star. Reach her at cheri.carlson@vcstar.com or 805-437-0260.

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