CDC relies on state-by-state tallies of death certificates to calculate the number of U.S. deaths from the new coronavirus, but state officials warn that the process is riddled with inaccuracies—and experts say the number of Americans who've died from the virus is likely higher than CDC's official count.

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US Covid-19 death toll tops 30K

As of Monday morning, U.S. officials had reported 753,317 cases of Covid-19, the disease caused by the new coronavirus and 36,109 U.S. deaths linked to the new coronavirus.

Covid-19 death count strategies vary between states

But health experts say inconsistent counting methods and a lengthy national data-gathering strategy likely mean the nationwide estimates of Covid-19 cases and deaths are inaccurate.

Until last week, CDC's national Covid-19 case and death counts only included cases and deaths that were confirmed with a laboratory test. However, CDC on Tuesday announced that it would begin including "probable [Covid-19] cases and deaths" in the totals because testing shortages hampered some states' ability to test every patient suspected of having Covid-19.

For instance, New York City—which is an epicenter of the United States' Covid-19 epidemic—this week began including presumed Covid-19 deaths in its count, which led to a significant spike in the number of Covid-19 deaths the city has reported. Officials said the additional deaths occurred among individuals who did not have lab tests confirming they were positive for the new coronavirus, but whose death certificates list Covid-19 as their suspected cause of death based on their medical histories and symptoms.

Delaware, Connecticut, Maryland, Ohio, and Pennsylvania also have started including probable cases and deaths in their reported tallies.

Other states have included probable cases and deaths in their tallies since they first began reporting the numbers, the Washington Post reports. Colorado, for instance, has included "epidemiologically linked" cases, or cases among people who were never tested for the new coronavirus but had contact with an infected person and showed symptoms of the disease, in its statewide death count since March. "Epidemiologically linked" cases accounted for about 3% of the state's Covid-19 death count as of Thursday.

In comparison, other states have unique counting strategies that can sometimes exclude even laboratory-confirmed cases of Covid-19 from their death tallies, the Post reports.

For example, in Alabama, a physician reviews the medical records of people who died and tested positive for Covid-19 to determine whether the death should be attributed to Covid-19 or to another underlying health condition. According to Karen Landers, a spokesperson for the state's Department of Public Health, Alabama's death count often excludes people who tested positive for Covid-19 but had no respiratory symptoms as well as people who experienced another health event, like a heart attack, when they had the disease.

As a result, out of the 110 people in Alabama who had tested positive for Covid-19 and died as of Thursday, 73 were included in the statewide death tally sent to CDC, the Post reports. Another 12 deaths were excluded, and 25 other deaths are still under review, according to the Post.

Deborah Birx, a physician who's leading the White House's coronavirus task force, said Alabama's strategy conflicts with CDC's approach to tallying Covid-19-realted deaths. "[W]e've taken a very liberal approach to mortality," she said. "[I]f someone dies with Covid-19, we are counting that as a Covid-19 death."

However, health experts said the nature of the disease, which can be mild and even asymptomatic in some, and the nation's testing hurdles inevitably will result in discrepancies in how Covid-19 cases and deaths are counted.

"Can there be disagreement in how these things are concluded? Absolutely," said Jonathan Arden, a forensic pathologist and chair of the board of the National Association of Medical Examiners. "You are talking about medical judgments, a diagnostic process that means you are arriving at an opinion."

Officials suspect underreporting of Covid-19

Meanwhile, city officials have told ProPublica that an increase in the rate of at-home deaths across the country could imply that the official U.S. Covid-19 death count is excluding a number of deaths that are occurring outside of hospitals.

ProPublica in a review compiled data from health agencies, police departments, 911 call centers, and vital-records departments to analyze overall death rates in states that house Covid-19 hot zones, including Massachusetts, Michigan, New York, and Washington. According to ProPublica, New York City officials last week recorded about 200 deaths per day that occurred outside of nursing homes and hospitals, compared with an average of about 35 such deaths per day between 2013 and 2017. Similarly, in Detroit, officials received more than 150 "dead person observed" phone calls within the first 10 days of April, compared with an average of about 40 during the same time period in recent years.

And in Middlesex County, Massachusetts, officials reported 317 at-home deaths in March this year, representing a 20% increase when compared with the number of at-home deaths reported during March in recent years, ProPublica found. The official Covid-19 death rate for the state was 89 in March, according to Massachusetts' Department of Public Health.

According to ProPublica, health experts have said the large increases in at-home deaths in these states could stem from deaths occurring among people who were infected with the new coronavirus, but who were not included in the states' overall Covid-19 death count due to a lack of access to treatment or testing.

However, some experts cautioned that the increases in at-home deaths in these states also could be tied to growth in the number of people dying at home from other conditions, such as heart attacks, because they either couldn't get to a hospital or were afraid to seek hospital care because of the Covid-19 epidemic.

'Just the tip of the iceberg'?

Still, Mark Hayward, a sociology professor at the University of Texas-Austin, said the discrepancies likely mean America's current official Covid-19 death count represents "just the tip of the iceberg" of how deadly the disease has been in country. "[T]he undercount is going to be really high" at the start of the epidemic, he said.

Robert Anderson, chief of CDC's mortality statistics branch, said national death counts based on death certificates always are an underestimate, even for common illnesses like the flu. Eventually, CDC likely will adjust its national death count for Covid-19 by comparing the total deaths recorded during the epidemic to historic death rates, Anderson said (Brown et al., Washington Post, 4/16; Bowden, The Hill, 4/16; Gillum, ProPublica, 4/14).