Coronavirus can spread from dead bodies, scientists say

Like a zombie in a horror movie, the coronavirus can persist in the bodies of infected patients long after they die, even spreading to other people, according to two startling studies.

The risk of contagion is primarily for people who handle dead bodies, such as pathologists, medical examiners and health professionals, and it occurs in settings such as hospitals and nursing homes, where there can be many deaths.

While dead body transmission is unlikely to be a major factor in the pandemic, bereaved family members should exercise caution, experts said.

“In some countries, people who have died from Covid-19 are being left unattended or taken back to their homes,” said Hisako Saitoh, a researcher at Chiba University in Japan who has published two recent studies on the phenomenon.

“So I think it’s information the general public should have,” she wrote in an email.

Several studies have found traces of infectious virus in cadavers up to 17 days after death. Saitoh and his colleagues went further, showing that dead bodies can carry significant amounts of infectious virus and that dead hamsters can transmit them to living cagemates.

The research has not yet been approved for publication in a scientific journal, but outside experts said the studies were well done and the results are convincing.

The risk of a living patient spreading the coronavirus is far greater than potential transmission from dead bodies, Saitoh and other scientists stressed.

If cadaver infection accounted for a large number of cases, “we would have noticed, right?” said Vincent Munster, a virus specialist at the US National Institute of Allergy and Infectious Diseases.

Still, “if there is an infectious virus, there is always a risk of transmission,” he continued. “I don’t think that’s often taken into account.”

In the United States, bodies are usually embalmed shortly after death or cremated. But in Holland, where Munster grew up, as in many parts of the world, family members are allowed to wash and dress the bodies.

In July 2020, the Japanese government asked bereaved family members to keep their distance from dead bodies and avoid touching, or even seeing, them. Officials also recommended sealing corpses in waterproof bags and cremating them within 24 hours.

The guidelines were revised in May 2022 to allow family members to see loved ones who have died from Covid but “in a hospital room with adequate infection control”.

These guidelines, in part, led Saitoh to explore what happens to the virus in the body after death.

She and her colleagues analyzed samples from the noses and lungs of 11 people who died of Covid. The researchers found that large amounts of virus persisted in 6 of the 11 cadavers, even 13 days after death.

“It was surprising that the infectious concentration was preserved at the same high levels as in clinical patients,” wrote Saitoh. “Most surprising, however, were the results of the animal experiments.”

In these, she and her colleagues found that hamsters that died a few days after being infected with the coronavirus could transmit it to other animals. In people, too, contagion is more likely when a patient dies soon after infection, when levels of virus in the body are very high, the researchers said.

The team found more viruses in the lungs of human cadavers than in the upper respiratory tract. This suggests that professionals performing autopsies must be particularly careful when handling the lungs, experts said. Saitoh pointed to a study from Thailand that describes a forensic doctor who appears to have become infected while on the job.

Gases that accumulate after death can be expelled through any orifice in the body, including the mouth, and can carry infectious viruses, the researchers said. Embalming or practicing so-called “angel care” — a Japanese ritual in which the mouth, nose, ears and anus are plugged with cotton wool — prevented transmission, they found.

Contagious corpses are not unknown. Funeral practices are known to have triggered major outbreaks of the Ebola virus in Africa.

But the coronavirus is very different, noted Angela Rasmussen, a research scientist at the Infectious Diseases and Vaccines Organization at the University of Saskatchewan in Canada.

Up to 70% of people infected with Ebola die, compared to around 3% of people diagnosed with Covid-19. And the Ebola virus floods every part of the body, so the risk of transmission, even after death, is much greater than theoretically posed by the coronavirus.

“With Ebola, it’s clearly direct contact with bodily fluids, because there are high levels of Ebola virtually everywhere from someone who has died of Ebola,” Rasmussen said.

She was initially skeptical that the coronavirus could spread from dead bodies, but found the new studies compelling.

“Most people probably still have to worry a lot more about catching Covid from their living neighbors than their recently deceased ones,” she said.

But “they must be very cautious about physical contact with the remains of their loved ones,” he added.

_{Translated by Luiz Roberto M. Gonçalves}