IRVINE, Calif.—We’re always hearing about the number of reported COVID-19 cases, positivity rates, deaths, and other metrics. But how is this information collected and reported? How accurate are these metrics? What do the stats say about how a region is doing overall?
Health officials have acknowledged and fixed data errors in Orange County and California in recent months—but even when data collection and reporting is operating as it should, there are nuances for people to understand.
“The particular number of cases [or] deaths reported on any particular day is not a meaningful metric,” Marc Meulman, Orange County’s acting director of public health services, told The Epoch Times.
For example, if the Orange County Health Care Agency reports five new COVID-related deaths on a Friday, that doesn’t mean five people died that day.
It means that’s how many deaths—which happened over the course of an indeterminate amount of time—were tallied up and reported that Friday. There are lags in reporting, and a seeming spike in deaths might actually be explained, in part, by a bunch of data coming through at once.
“It is always important for cases and for deaths, to look at the data for cases by specimen collection date and deaths by date of death,” Meulman said. “Monitoring the data this way removes the various reporting delays and provides a better picture of the course of disease transmission and impact.”
He said reporting lags are built into the methodology for analyzing the data that officials use to make decisions about level of risk in a region and reopening.
“Due to various potential delays in the process, the criteria used for decision-making have lags built into the methodology to allow time for the data to be more complete,” Meulman said.
Co-existing Health Conditions
Regarding the number of deaths, there’s also the question of deaths by COVID-19 alone versus those that involve other health conditions.
Dr. Charles Bailey, medical director for infection prevention at St. Joseph Hospital and Mission Hospital in Orange County, explained to The Epoch Times how COVID-19 is determined as a cause of death.
Anyone who had a positive COVID-19 test and died is counted as a COVID-19-related death, “regardless of whether [other] illness is present,” Bailey said.
If someone has a motor vehicle accident or a fatal heart attack, he said, if the person tested positive for COVID-19, that’s counted as a COVID-19 death.
Nonetheless, the data handed over to officials does note cases in which other health conditions may have contributed to the death.
“We do attempt to determine whether a death in a COVID patient was due to the COVID infection itself,” Bailey said.
Even in patients that have other conditions, COVID-19 may be what caused those conditions to become fatal, he said.
“If not for COVID, this patient most likely would not have passed away,” Bailey said of one type of case. In another type of case, “The presence of COVID likely did not contribute to the fatal outcome.” Meaning COVID-19 is unlikely to have “caused” the death, the co-existing health condition did.
The Centers for Disease Control and Prevention website states: “For 6 percent of the deaths, COVID-19 was the only cause mentioned. For deaths with conditions or causes in addition to COVID-19, on average, there were 2.6 additional conditions or causes per death.”
So, 94 percent of reported COVID-19 deaths nationwide have occurred with people who have underlying health conditions, generally more than two.
Positive Tests and Ratios
Another metric officials look at is the ratio of positive tests to the number of tests administered.
“By itself, [that] only tells us what percentage of people being tested have positive results,” Meulman said.
If more people are being tested all of a sudden—whether it’s because tests have been made more available to the community or for whatever reason—that ratio number could change. But it doesn’t necessarily mean the rate of COVID-19 transmission has changed.
Bailey said trends in patients hospitalized with COVID-19, and especially those patients who require ICU care, are more useful metrics to track the impact of the disease on a community.
The number of positive tests or cases “may be the result of test availability and community concern, as well as actual disease prevalence and severity,” he said.
Meulman also noted that, as with all tests for illnesses, there’s a margin of error. That margin for COVID-19 testing varies, Meulman said, “depending on factors including the type of test and method of specimen collection.”
“No test is perfect, so false positives [or] negatives may occur occasionally,” Meulman said. “This is not unique to COVID testing.”
Impacts to Decision-Making
All these metrics are being used by officials to determine regulations, including when to allow certain activities to resume, how to reopen all the things that have closed since March.
Meulman said that given the nuances of each metric, the best assessments are being made by combining those metrics.
“All the data-points together help provide a picture of what is happening in the community,” he said.
Relying solely on test results to make decisions would likely result in a skewed picture of the overall situation, he said. “But this is why we look at multiple data, including testing volume, positivity rate, hospitalization data, deaths. All of the data is important and informative.”