Long Covid has caused or contributed to at least 3,500 deaths in the United States, an analysis of death certificates by the Centers for Disease Control and Prevention found.
The study, published on Wednesday, is believed to be the first nationwide examination of whether long Covid or related terms appear in official American death records. While it found that such phrases were recorded in only a tiny proportion of the more than a million deaths tied to infection with the coronavirus, the researchers and other experts said the results added to growing recognition of how serious long-term post-Covid medical problems can be.
“It’s not one of the leading causes of death, but, considering that this is the first time that we’ve looked at it and that long Covid is an illness that we’re learning more about day after day, the major takeaway is that it is possible for somebody to die and for long Covid to have played a part in their death,” said Farida Ahmad, a health scientist at the National Center for Health Statistics at the C.D.C. who led the study.
Long Covid is a complex constellation of symptoms that can last for months or longer and can affect virtually every organ system. Some of the most debilitating post-Covid symptoms are breathing problems, heart issues, extreme fatigue and cognitive and neurological issues.
The researchers looked at death certificates in every state and Washington, D.C., dated from Jan. 1, 2020 to June 30, 2022. They found 1,021,487 certificates that included a diagnostic code for Covid-19 as an underlying or contributing cause of death. Of those, 3,544 — or 0.3 percent of the total — listed long Covid or terms like post-Covid syndrome, chronic Covid or long-haul Covid.
Ms. Ahmad and experts not involved in the research said the number of deaths related to long Covid in the study was almost certainly an underestimate. It has taken time for the condition to be recognized and identified by doctors and other medical providers. And the study was not able to include a new diagnostic code for long Covid because it was not yet being used in reporting of deaths in the United States, the researchers said.
“This new research is important in raising a concern, but it should be followed with more definitive work,” said Dr. Jeffrey Martin, chief of the division of clinical epidemiology in the department of epidemiology and biostatistics at the University of California, San Francisco, who was not involved in the research.
“Historically, death certificates have been incomplete in explaining how a person died,” said Dr. Martin, who suggested that future research should include interviewing patients’ doctors and family members and evaluating their medical records.
The study found that more death certificates mentioned long Covid after 2020 and that the condition was more likely to be listed on death certificates in the weeks or months after a peak of Covid cases, Ms. Ahmad said.
The study found that some of the long Covid patterns related to age, sex, race and ethnicity differed from those seen in deaths caused by the initial infection. For example, while Black and Hispanic people had higher death rates from the initial coronavirus infection than non-Hispanic whites, those groups did not have higher death rates related to long Covid, the study found.
The researchers suggested that the difference might be partly because of systemic disparities that have resulted in less access to health care for Black and Hispanic patients, who might not have received appropriate long-Covid diagnoses. The study said it was also possible that, because Black and Hispanic patients died at higher rates from the initial illness than white patients, they might have “fewer Covid-19 survivors left to experience long-Covid conditions.”
Nearly 57 percent of deaths related to long Covid were in people 75 and older. Nearly a third of the death certificates that mentioned long Covid listed the underlying or main cause of death as a non-Covid condition such as heart disease, cancer or Alzheimer’s.
“This is just scratching the surface — this is a first look,” said David Putrino, the director of rehabilitation innovation for the Mount Sinai Health System in New York, who was not involved in the study.
He said the study appeared to be primarily capturing deaths of people who experienced serious initial infection with the coronavirus and who survived that phase but went on to have organ damage and other severe complications. He said other deaths related to long Covid should be studied, including deaths by suicide of people who had devastating post-Covid symptoms.
Another report published on Wednesday, by the Documenting Covid-19 project, offered a snapshot of deaths related to long Covid by looking at death certificates in 2020 and 2021 in Minnesota, New Mexico and a few other locations. That report, conducted by the Brown Institute for Media Innovation at Columbia University and MuckRock, a public records foundation, found that 18 of the 28 deaths associated with long Covid in Minnesota during those years were in people over 80 years old and that most of the patients had worked in blue-collar jobs and lacked a college degree. In New Mexico, about a third of the 13 deaths related to long Covid were in people under 60, and some were frontline or essential workers, the report said.
Experts evaluating the C.D.C. study cautioned that it was both an incomplete picture of mortality linked to long Covid and of the larger toll of the condition, which has been estimated by the Government Accountability Office to have affected 7.7 million to 23 million people in the United States.
“This is an important thing to explore and study, but it shouldn’t be used as a proxy for saying, Oh, well, long Covid isn’t that severe because look how few deaths there are,” Dr. Putrino said. “We should not be measuring the damage that long Covid does by deaths alone.”