Scientists find clues to long covid causes

Pfizer’s Paxlovid antiviral box placed in a warehouse in Shoham, Israel, January 18, 2022. (Kobi Wolf / Bloomberg)

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Researchers have discovered that patients with Covid-19 may carry the coronavirus in their faeces for several months after infection, and its persistence can worsen the immune system and cause long-term Covid symptoms. I am concerned that there is.

In the largest study to track the symptoms of SARS-CoV-2 RNA and Covid in feces, scientists at Stanford University in California found that about half of infected patients discarded traces of the virus one week after infection, nearly four. 7 months after discovering that% of patients are still releasing the virus. The researchers also concluded that coronavirus RNA in feces was associated with gastric upset and that SARS-CoV-2 could directly infect and hide the gastrointestinal tract.

Ami Bhatt, senior author of a study published online in the journal Med on Tuesday and associate professor of medicine and genetics at Stanford University, said: .. Residual viruses can invade cells directly, damage tissues, and produce proteins that stimulate the immune system, she said in an interview.

No one knows yet the cause of the constellation of post-Covid symptoms, often referred to as long Covids, that afflict 5% to 80% of people after SARS-CoV-2 infection. Akiko Iwasaki, a professor of immunobiology and molecular, cellular, and developmental biology at Yale University, said at least four different biological mechanisms could lead to different states or subtypes of long Covids.

“Long Covid is likely to have several different illnesses,” Iwasaki said last week in an interview in her lab in New Haven, Connecticut. In one of these forms, she said, persistent SARS-CoV-2 can provoke a detrimental immune response, leading to illnesses that can be sedated by virus-targeting drugs.

“I’ve heard of people recovering from long Covids after antiviral and monoclonal antibody therapies,” said Iwasaki, who wants to collaborate in clinical research on potential therapies. .. She told Long Covid she was “really excited about the possibility of testing direct antivirals and monoclonal antibodies.”

Pfizer’s Paxlovid received an emergency use authorization from the Food and Drug Administration in December and introduced the first Covid treatment in the form of tablets. Pfizer hasn’t been working on Covid for a long time, but is appreciating its potential, the drug company said in an email.

When an antiviral product is fully approved, it will not be approved as it is now, but researchers will have more freedom to study in combination, and will be responsible for the AIDS department of the National Institute for Allergic Infectious Diseases. Karl Diffenbach said. Diefenbach is also co-leading an antiviral program to combat the pandemic threat.

Some scientists believe that Omicron and its submutants have evolved in a single patient suffering from a long-term Covid infection. Drugs that accelerate the elimination of such infections may reduce the risk of the emergence of new antigenic strains.

SARS-CoV-2 is transmitted primarily through respiratory particles released from the respiratory tract of the infected person. However, it is difficult to show that feces contain infectious particles. Live viruses need to be isolated, purified and tested from microbial-rich feces in a laboratory specially equipped to treat dangerous pathogens.

The gastrointestinal tract is a major extrarespiratory site for SARS-CoV-2 persistence and regular viral shedding, Chinese researchers showed in 2020. Traces of the virus were identified in the faeces within weeks of the appearance of Covid and encouraged the use of wastewater. Monitoring to measure the spread of the pandemic.

“The gut is one place where people report persistent antigens and RNA,” Iwasaki said. Others report evidence of persistence of lymphoid tissue, brain, and other organs from autopsy performed primarily on people who died of severe, acute attacks in Covid. “It’s not clear how much is really happening in long Covid patients,” she said.

According to Bat of Stanford University, there is little data on the frequency and duration of coronavirus in the stools of people with mild to moderate covid. In May 2020, as part of another study, she and her colleagues began monitoring long Covid symptoms and the extent and location of people’s viral shedding.

When researchers analyzed fecal samples from 113 participants at a particular point in time after infection, about 13% released viral RNA 4 months after they removed the virus from the respiratory tract. .. Two participants had evidence of the virus in their stool about 210 days after infection.

Researchers have also isolated enough viral RNA to determine which mutant infects a participant, and that the samples isolated from a particular individual at early and late stages are of the same strain. I couldn’t even show it in the end. Nevertheless, specimens were collected during the first year of the pandemic, reducing the likelihood of reinfection with a second strain or mutant during the study period.

Bhatt, who is trained as a cancer physician and is studying the interaction of gut microbiota with patient outcomes, says the new findings will improve the understanding of clues that can be collected from sewage regarding community infections with the coronavirus.

“When we look at wastewater-based epidemiology and try to interpret it, it’s important to understand how many people are shedding for how long,” she said.

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Riley Griffin of Bloomberg contributed to this report.