Why You Should Be Worried About Utah’s COVID-19 Test Positivity Rate

One of the most closely watched – and often the most alarming – data points of the COVID-19 pandemic is the test positivity rate.

It’s a simple metric: out of all the COVID-19 tests processed, how many of them are positive?

But Utah’s actual rate – which hit 32.2% on Monday – is more complicated to calculate, as some amateur data analysts have discovered.

For example, the Utah Department of Health reported on Sunday that the seven-day moving average of the test’s positivity rate was 29.7%. (Public health officials use seven-day averages for many metrics, as they reveal general trends rather than the wider up-and-down swings of daily reports, leveling out factors such as weekends and days. holidays.)

But if you take the number of positive cases in the previous seven days – 18,599 – and divide it by the total number of tests processed, which was 52,576 for the seven days ending Sunday, you’d get a figure of 35.4 %.

David Nierenberg, an airline pilot living in Salt Lake City, found similar discrepancies when looking at UDOH numbers last week.

“The last days of reporting on percent positivity have been turned off,” Nierenberg wrote to the Salt Lake Tribune last week. “Could you please publish the actual number tested over the past week in the next article to correct the record?”

So why is the state’s official positivity rate different and lower? With the daily figures released by UDOH, “you don’t have all the negative results taken into account,” explained Tom Hudachko, a spokesperson for the department.

Positive test results are reported faster than negative ones, so UDOH sets in a certain amount of time – usually around five days – for negative results to catch up, Hudachko said. Without this lag, the positivity rate would be artificially high, he said.

A positivity rate hovering around 30% is alarming as it stands. Public health experts say that such a high positivity rate is an indicator that many people have the virus and are not getting tested.

Dr. Todd Vento, an infectious disease physician at Intermountain Healthcare, noted Monday that Utah this weekend ranked ninth out of 50 states for its test positivity rate.

“We still have some positive transmission,” Vento said during an online press briefing on Monday.

“Testing is important, but that’s not how you get out of a pandemic. You are not testing your way out of a pandemic, ”Vento warned. “You are preventing and stopping the spread of disease. This is how you get out of a pandemic. “

Government officials, Vento said, “fell into this trap early on” that “we just have to test more to show that we have more negatives. [tests]. This is really the wrong approach. The correct approach is that we need to test more to find out the truth. “

The UDOH aims for a test positivity rate of 5%, Hudachko said. This low rate, Vento said, “would show excellent control” over the spread of the virus. “We haven’t been at 5% for months and months, and neither have many states in the United States,” Vento said.

The way to bring down the test’s positivity rate, Vento said, is to get people vaccinated and, until that happens, to keep doing what health experts have been saying for months: by public and in contact with others. You must stop gathering, and [you have to be] keep your physical distance.

Vento added: “The message is not going to change because the calendar year has changed. The message is the same. “

This story is developing and will be updated.