The Middletown Press (Middletown, CT)


Changes to testing in CT makes tracking cases more complicate­d

- By Alex Putterman

How nervous you are right now about Connecticu­t's COVID-19 uptick might depend on which metric you're tracking.

By test positivity rate, Connecticu­t is in crisis. Over the past week, more than 11 percent of the state's tests have come back positive, a level not previously recorded since January, amid the state's winter surge.

By case counts, on the other hand, the situation appears more manageable. As of Friday, Connecticu­t had averaged 900 cases a day over the past week, up from about 300 a day during parts of March, but nowhere near the 10,000 a day the state saw in mid-January.

So which of the two metrics is truly accurate in representi­ng Connecticu­t's current level of COVID-19? Well, maybe neither one.

Due to changes in how tests are reported, as well as the emergence and popularity

of at-home testing, experts say both positivity rate and case counts have become skewed, making comparison­s with previous COVID-19 waves difficult. This comes as hospitaliz­ation totals, another stalwart metric throughout the pandemic, are distorted by the presence of “incidental” cases — those in which someone tests positive for COVID-19 after being hospitaliz­ed for an unrelated reason.

The result: A lot of confusion about Connecticu­t's true level of transmissi­on, among those who follow the pandemic profession­ally and the general public.

“We're still grappling with recognizin­g the limitation­s of the data that's available,” said Dr. David Banach, hospital epidemiolo­gist at UConn Health. “I'm still struggling, and I think a lot of people are, with how to interpret it.”

Imperfect metrics

The COVID-19 metrics reported each day by the state Department of Public Health have always been flawed and incomplete in certain ways, but during previous waves they at least offered a common language with which to discuss the pandemic: A 5 percent positivity rate was high, while a 10 percent positivity rate was extremely high. If your town was in red on the state's case map, maybe it was time to mask up.

But the emergence of athome testing has changed that in a hurry. Unlike during previous COVID-19 waves, when nearly all test samples were collected by care providers and reported to DPH, patients are now able to test themselves, with no obligation — or even ability — to report their results to health authoritie­s.

This, of course, has led to a dramatic under-counting of cases. Dr. Scott Gottlieb, a Connecticu­t resident and former head of the Food and Drug Administra­tion who has closely followed the pandemic, estimated last month that the Northeast was detecting “one in seven or one in eight [COVID-19] infections.”

But while home tests have led to an under-counting of cases, they may be contributi­ng to an inflation of Connecticu­t's positivity rate, as asymptomat­ic people who need a negative test to see family or attend an event are now more likely to stick with an at-home test, leaving PCR tests for those with significan­t symptoms.

“Why is our positivity 10 percent? In part, because I think the people getting PCRs already know they're positive and want that confirmati­on by PCR, or had been testing negative on self-test kits, but are symptomati­c and are going in and getting a PCR,” Dr. Manisha Juthani, Connecticu­t's public health commission­er, said last week. “So I think our positivity rate does not necessaril­y reflect what it did before.”

The state has also recently tweaked how it reports COVID-19 tests, no longer sharing negative results from rapid tests, which previously accounted for about 10 percent of the state's total. That means thousands of negative samples are missing from the denominato­r of Connecticu­t's high positivity rate.

Amid these changes, Banach says it has become difficult to rely on positivity rate or to compare the current numbers against what the state experience­d earlier in the pandemic.

“The positivity rate, I'm still trying to understand how to interpret that based on what the denominato­r is, because I think that's a little unclear right now,” he said.

But the confusion doesn't stop there. Whereas hospitaliz­ations were once a reliable way to gauge how many people were seriously ill, albeit with a lag of a week or two, those numbers are now inflated by people who arrive at the hospital for one reason, then test positive for COVID-19 upon arrival. These incidental cases can make up as many as 60 or 70 percent of total hospitaliz­ations, one Hartford HealthCare official said Friday.

And while deaths are, in the end, perhaps the most important metric of all, they lag weeks behind cases, and therefore, have never been especially useful in revealing the state of a COVID-19 spike at a particular moment.

It was likely with all this confusion over metrics in mind that the Centers for Disease Control and Prevention created its COVID-19 threat maps, offering countyby-county risk assessment­s. But even there, the data has become cloudy. The CDC drew criticism earlier this year for drasticall­y changing the thresholds used for its signature map, turning highrisk counties into low-risk counties overnight.

Based on the CDC's old map, all of Connecticu­t easily meets the criteria for “high transmissi­on” and has for a while. Based on the new map, three counties narrowly qualify as for the “high” category, while four others are still “medium.”

All told, Connecticu­t residents have access to plenty of data — little of it easy or straightfo­rward to interpret.

The tools available

Still, it's clear that COVID-19 is present in Connecticu­t in large numbers, and with enough context, it's possible to evaluate how much.

Wastewater surveillan­ce in New Haven, for example, shows a sharp increase in COVID-19 over the past month, but suggests that transmissi­on has plateaued at a level far lower than the state experience­d over the winter.

Banach said he looks at the CDC's community transmissi­on map, the more cautious one, as a tool in assessing a community's risk level. He also considers hospitaliz­ations a valuable measure, less for determinin­g how many people are seriously ill and more for tracking how many people are showing up at hospitals with the disease.

Dr. Ulysses Wu, chief epidemiolo­gist at Hartford HealthCare, said he's concerned less about absolute case counts and positivity rates and more about trends in those numbers. Because while those two metrics might now be telling different stories, they're both pointing in the same direction.

“We are still following the same metrics,” Wu said. “We are looking at positivity rate, we're looking at hospitaliz­ations, we're looking at vaccinatio­n rates, we're looking at deaths, we're looking at ICU data.”

The balance of evidence suggests Connecticu­t has seen a significan­t rise in COVID-19 transmissi­on — maybe more significan­t than was initially predicted when this uptick began in March — but nothing resembling the state's winter surge, when hospitals struggled to find staff and space amid a crush of patients.

What may ultimately be most important to know, experts say, is simply that COVID-19 is present in Connecticu­t in large quantities, more than enough for residents to consider taking precaution­s to protect themselves and their families.

 ?? Ned Gerard / Hearst Connecticu­t Media file photo ?? Changes in how coronaviru­s tests are reported have distorted the metrics experts and regular citizens have come to rely on throughout the pandemic.
Ned Gerard / Hearst Connecticu­t Media file photo Changes in how coronaviru­s tests are reported have distorted the metrics experts and regular citizens have come to rely on throughout the pandemic.

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