COVID-19 Colorado: Some Virus Deaths May Never Be Confirmed

The hottest COVID-19 topic at this stage of the crisis in Colorado involves testing and the key questions surrounding it. When, if ever, will on-demand testing be available? Are shortages of supplies finally starting to ease? Do we have any firm idea of how many people have been infected by the novel coronavirus, and how many have died from it? And what about those disturbing reports from the federal Centers for Disease Control and Prevention about "excess deaths"?

In an effort to get the most current answers possible, we reached out to officials at the Colorado Joint Information Center, which is handling communication duties for the state during the pandemic. The answers provided by the JIC crew via email are impressively detailed and thorough, as well as notably frank.

For example, CJIC staffers concede that some data simply isn't being tracked at this point, and acknowledge that we may never know the actual death toll from COVID-19 for a variety of reasons.

Here's much more on the good, the bad and the ugly in the state's fight against the virus.

Westword: What is your approach to data in regard to combining information about positive and presumptive positive COVID-19 cases?

Colorado Joint Information Center: We no longer use the term “presumptive positive.” It was used early on, when the CDC was confirming test results from states. Positive tests were called “presumptive positive” until CDC confirmed them. CDC stopped asking to confirm test results back in March, and we stopped using the term “presumptive positive.”

We do describe cases as either confirmed or probable. This is a standard method in public health that we use for other types of conditions. We follow the CDC-accepted case definition for COVID-19, which includes both cases with positive tests and other cases with strong evidence for COVID-19, which we call “probable cases.” The total number of cases we report includes both confirmed and probable cases. Right now, probable cases make up about 10 percent of the total, which has been fairly stable over time. Here are definitions for each:

Cases are considered confirmed when there has been a positive molecular amplification test (such as PCR) performed by a lab. These tests commonly involve taking a nasal swab, which is then sent to specific laboratories for results. A molecular amplification test detects genetic material from the virus indicating presence of the virus.

Cases are considered probable when they meet one of the following criteria: A person exhibited symptoms AND had close contact with someone who tested positive OR a person exhibited symptoms AND tested positive using an antigen or serologic test (an antigen or serologic test is a blood test that looks for antibodies in your blood; this test can detect the body’s immune response to the infection caused by the virus rather than detecting the virus itself) OR a person has an epidemiologic link AND has tested positive using an antigen or serologic test (an epidemologic link is close contact with a confirmed or probable case of COVID-19 disease OR travel to or residence in an area with sustained, ongoing community transmission OR a member of a risk cohort as defined by public health authorities during an outbreak) OR a death certificate lists COVID-19 disease or SARS-CoV-2 as a cause of death or a significant condition contributing to death with no confirmatory laboratory testing performed for COVID-19.

Are there fewer probable cases now than there were a few weeks ago, and if so, why?

We are not tracking the change in ratio of probable cases to confirmed cases over time.

Approximately what percentage of cases are initially listed as probable, and what percentage are confirmed as positive at some later point?

Probable cases are usually identified through investigations into outbreaks where there are confirmed cases. We are not tracking the percentage of probable cases that later get confirmed through lab testing.

Are there some probable cases that will likely never be confirmed, and if so, what are the reasons and what's a best guess about percentages?

Yes, not all probable cases get tested, so some will never be confirmed. We don’t have a percentage. Testing requires adequate testing samples and reagents, as well testing equipment, and there is a worldwide shortage, so it has not been possible to test every probable case. We are scaling up our testing capacity, though, and testing people who may have COVID-19 is always a priority.

Does your data about positive and probable cases include data from private labs at this point, and if so, how promptly are you receiving that information — and is there potential lag time between reports of positive cases from private labs that sometimes results in what appear to be big bumps in totals?

Probable cases include those with positive blood test results, which do come from private labs. If someone with a positive blood test result later got a positive PCR test result, their case would be changed from probable to confirmed. The majority of all test results does come from private labs, and the time it takes them to report results varies. We did recently have a large bump in positive cases due to Quest Diagnostics reporting a large number of previously backlogged cases at once.

" We still prioritize testing for people with symptoms in most cases because they are the ones most likely to spread the disease."

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We frequently hear about false negatives in COVID-19 tests. What is your best guess about the percentage of false negatives in testing overall, and is there any way to factor that into the number of overall cases?

The PCR test we are using has a very high sensitivity range. That means the test can trace extraordinarily low amounts of the COVID-19 virus. In addition, it has a 100 percent specificity rate, which means it’s designed to detect only COVID-19, and not other viruses. The actual sensitivity percentage achieved is dependent on numerous factors, including whether the sample was taken properly, if it was kept cold, as well as the stage of infection of the patient. We are not concerned about false positives, but false negatives may occur in people that are tested too early in their incubation.

During a recent press conference, when the number of positive tests was around 10,000, Governor Jared Polis said it's likely that meant there were 65,000 to 75,000 positive cases in the state. In light of this comment, should we multiply positive test totals by 6 or 7 to get a better idea of the true infection rate, and if not, what's the best way to get a more complete picture?

This is based on our modeling data, and it's a simple multiplication factor to estimate disease burden. The models use many different inputs to come up with estimates of case burden.

Are the numbers of probable COVID-19 deaths falling as testing is becoming more available, and if so, what's the percentage now as compared to April 1?

Information about deaths comes in from many sources and at different times. We are not tracking changes to the ratio of probable to confirmed deaths over time.

Is it likely that some people died of COVID-19 prior to the official designation of the first death or early on in the spread that may not have been attributed to the virus but should have been — and what's your best guess about how many that might be?

It’s possible, but we don’t have a number for this. Over time, additional data linkage and analysis work will help us to identify more previously unattributed COVID-19 deaths.

In an ideal world, would everyone in Colorado, including those who are asymptomatic, be tested for COVID-19 — and if so, is that a realistic possibility for some point down the line?

There is a worldwide shortage of PPE and test supplies, so we are working to maximize the usefulness of the supplies. This means that testing is prioritized for symptomatic people and targeted asymptomatic people such as health care workers who work with vulnerable populations.

Is it your advice that asymptomatic people be tested at this point, with more tests available — or should they wait until when and if they exhibit symptoms, and if so, why?

We still prioritize testing for people with symptoms in most cases because they are the ones most likely to spread the disease. For some of our recent testing initiatives at large facilities, we are now testing asymptomatic people so that we can better control the risk of disease spread.

Have we reached an infection peak for this wave of the virus, and if so, when did it likely occur?

We’re in the early stages of this pandemic. New infections have recently plateaued or declined slightly across most of the state, but that should be seen as a response to the effectiveness of our physical distancing measures rather than a peak in the pandemic’s course.

Is a second wave of infections all but assured at this point, or can one be prevented if we all maintain proper social distancing, wear masks when out in public and practice other best practices?

The disease is present in Colorado, so we would expect the rate of infections to respond to changes in physical distancing measures. The goal of Safer at Home policies is to let people engage in more economic and physical activity while still making sure our health system has the capacity to treat people who do get sick.

How would you characterize our success at achieving social distancing and mask use by percentage, and are there concerns that the percentage will decline if the number of cases and deaths begin to go down, thereby increasing the odds of a second wave?

We estimate that we achieved 75-80 percent physical distancing under the Stay at Home order, which means there were about 75-80 percent fewer close interactions between people. The goal under Safer at Home is to reopen aspects of the state responsibly in a way that will reduce physical distancing to 65 percent, which our modeling data tells us should not overwhelm hospital capacity.

Are you optimistic about our chances of avoiding a second wave at this point?

We are in the early stages of a pandemic, not at the end of a wave. Our goal is to maintain a level of physical distancing that will keep our hospitals from being overwhelmed while reopening the state as much as possible.