Covid could potentially spread from corpses to the living in a zombie-like fashion, two new studies suggest.
Scientists in Japan found traces of the coronavirus in the nasal passages and lungs of recently-deceased human and hamster corpses as many as 17 days post-mortem.
They warned that while the risk of transmission from cadavers to the general public is low – mainly confined to medical examiners, pathologists, and healthcare workers – those people and grieving families should be cautious.
‘It is possible that infectious viruses are transmitted via the postmortem gases produced by the decomposition process or other postmortem changes in the dead body,’ authors of one of the studies wrote.
In one study on rodents, researchers infected a group of hamsters with the coronavirus and euthanized them 24 to 48 hours later.
Their bodies were then disinfected in an alcohol bath for 30 seconds and wrapped with a wire net to prevent them from being cannibalized by living hamsters in the same cage.
They separated the hamsters into two groups. In one cage, they placed one wrapped body and two uninfected hamsters, and in the other cage, they put one live infected hamster and two uninfected hamsters together.
Twenty-four hours later, they found high titers, or residual antibodies from infection, in the live hamsters’ lungs and noses.
Covid was transmitted from all live infected hamsters under both conditions of cohousing, while the dead infected hamsters maintained high titers of virus in their lungs and noses 24 hours post-mortem.
A traditional Japanese burial method, in which cotton pads are used to plug the cadaver’s nostrils, mouth, ears and rectum, trapping in the gasses that naturally escape when a person dies, was also found to prevent transmission.
The custom, called Angel care, effectively prevented transmission from a dead hamster.
In the study involving humans, the Japanese scientists collected eight nose swabs and 11 lung specimens from 11 autopsy cases with Covid in 2021 and investigated the viral strains’ genetic makeup.
Their results showed the virus was present in six of the 11 cases. Four of those 11 cases were found through nasal swabs, while nine of 19 lung specimens showed evidence of the virus as many as 13 days after death.
‘Therefore, appropriate infection control measures must be taken when handling corpses,’ they concluded.
The Japanese health ministry this week decided to walk back pandemic-era funeral restrictions which urged bereaved family members who were close contacts of the deceased to refrain from touching or viewing the bodies, or even attending their funerals, depriving many families the opportunity for a final goodbye.
The ministry said the guidelines, which were set in July 2020, are set to be lifted by year’s end.
This is not the first time scientists have found cadavers can maintain traces of infectious disease and potentially spread them to others.
A 2021 study found that the infectious virus was still present in one of the COVID-19 corpses 17 days post-mortem, despite already visible signs of decomposition.
Meanwhile, a 2020 study out of Thailand reported that a person working on cadaver that died with Covid-19 in a forensic medical unit became infected soon after.