Corrections & clarifications: A previous version of this story stated that Bob Anderson, chief of the mortality statistics branch at the National Center for Health Statistics, believed that up to 1 in 3 death certificates nationwide were incorrect before COVID-19. Anderson clarified his estimate to be between 20 and 30 percent.

As the United States struggles to track coronavirus fatalities amid spotty testing, delayed lab results and inconsistent reporting standards, a more insidious problem could thwart the country's quest for an accurate death toll.

Between 20 and 30 percent of death certificates nationwide were wrong before COVID-19, Bob Anderson, chief of the mortality statistics branch at the National Center for Health Statistics, said in an interview with the USA TODAY Network.

“I’m always worried about getting good data. I think this sort of thing can be an issue even in a pandemic,” Anderson said.

Experts said the inaccuracies are part and parcel of a patchwork, state-by-state system of medical examiners, coroners and doctors who have disparate medical backgrounds, and in some cases none at all.

The problem is likely to get worse as the pandemic inundates overworked and sometimes untrained officials who fill out the forms.

Accurate death certificates are paramount for health officials trying to determine where to focus resources to fight the spread of the coronavirus, said Umair Shah, executive director of the Public Health Department in Harris County, Texas, which includes Houston.

“That death represents an ecosystem of people,” Shah said.

Inaccurate death reporting is a long-standing problem.

A review of Missouri hospitals in 2017, for example, found nearly half of death certificates listed an incorrect cause of death. A Vermont study found 51% of death certificates had major errors. Nearly half of the physicians the Centers for Disease Control and Prevention surveyed in 2010 admitted that they knowingly reported an inaccurate cause of death.

Death certificates regularly lack enough details to accurately pinpoint the cause of death, Anderson said.

“For example, cardiac arrest is not an acceptable cause of death, because everybody dies of cardiac arrest,” Anderson said. “That just means your heart stopped.”

Lack of expertise

The widespread inaccuracy of death certificate information stems largely from the varying levels of expertise of those who complete the forms, experts said.

Physicians, coroners, medical examiners, and in some states, other medical personnel, such as nurse practitioners, can legally sign death certificates, said Sally Aiken, president of the National Association of Medical Examiners and a practicing medical examiner in Spokane County, Washington.

Coroners and medical examiners are responsible for certificates in homicides, accidents and suicides, Aiken said. Physicians fill out the form when natural deaths, such as those caused by COVID-19, occur in a hospital. Medical examiners and coroners do it if the person died at home or in another non-health-care setting.

Medical examiners are generally physicians specializing in forensic pathology who can perform autopsies.

Coroners are not always doctors. In Alabama and Georgia, the only requirement for coroners to be elected is that they be nonfelons of legal age.

Even those with medical expertise regularly get it wrong. In Vermont, there are no coroners. If a death is natural or happens in a hospital or out in the community, physicians, nurse practitioners or physician assistants fill out death certificates. The state medical examiner’s office, which investigates violent deaths, reviews about 5,000 certificates each year to find and fix errors.

When the state medical examiner’s office compared 601 death certificates completed from July 1, 2015, to Jan. 31, 2016, with medical records, it found 51% had major errors.

Lauri McGovirn, a medical examiner who worked on that review, said some physicians didn’t complete death certificates regularly, so they were unfamiliar with the process. Others viewed it as an administrative chore.

“It does make you wonder in other states where they don’t have the type of resources or the money to review every death certificate, what their error rate may be,” McGovirn said.

Shortage of workers

In addition to expertise gaps, there’s a severe shortage of medical examiners nationwide.

In a report to Congress, the Justice Department said as many as 700 more forensic pathologists are needed. The report noted that in addition to staffing, “budgets, resources and supplies are too inconsistent to ensure that death investigations are of the same quality across the United States.”

Dr. Ray Fernandez has been the chief medical examiner for Nueces County, Texas, for 19 years. He knows what the shortage means — a punishing workload.

Despite hiring another full-time pathologist and two part-time pathologists several years ago, he and his colleagues each perform 200 to 300 autopsies per year, regularly bumping up against the National Association of Medical Examiners’ recommendation of no more than 325 per year.

The organization has temporarily suspended that caseload limit amid due to COVID-19, but Fernandez said the more cases medical examiners take on, the greater the chance they’ll make mistakes.

“COVID-19,” he said, “is impacting the system at a time when it’s already in a crisis with a shortage of people doing the work.”

To further complicate efforts to curb the spread of coronavirus, many medical examiners and coroners refuse to attribute a death to COVID-19 without a positive test before the person died. Some medical examiners are doing post mortem testing if they have the means. But with tests in short supply, that’s not always possible.

Dr. James Gill, vice president of the National Association of Medical Examiners and the chief medical examiner for the state of Connecticut, said he’s sending his staff to funeral homes to swab the noses of the deceased, which are then analyzed by an outside lab.

The family of the deceased and the first responders who attended to them need the lab results to know whether they should self isolate or get treatment, Gill said.

“You have to remember, though, that even if we are doing a swab on a dead person, those results may affect the living,” Gill said.

The National Center for Health Statistics, where Anderson works, updated its website on April 1 to clarify that those filling out death certificates should record COVID-19 as the probable cause if testing isn’t possible and if the medical records or circumstances support that.

Despite this, Anderson said, some physicians will simply list the cause of death as pneumonia when the pneumonia likely came after a COVID-19 infection. But he hopes fewer do.

“The fact is, a lot of these deaths are not going to be autopsied and post mortem testing is not going to be done, so we’re going to have to rely on second-hand accounts and what the symptoms were,” Anderson said. “We may miss some as a result.”