This is an excerpt from Second Opinion, a weekly newsletter on health and medical sciences. If you have not yet subscribed, you can do so by clicking here.
When Omicron began to spread rapidly around the world, theories about its origins also surfaced.
Did the severely mutated coronavirus evolve within an animal host before being transmitted back to humans or in a COVID-19 patient treated with a drug capable of inducing viral mutations?
Or, as many scientists have wondered, did the latest worrying species evolve during a long battle against the virus inside the body of someone with a weakened immune system?
While there are no clear answers yet to questions about the emergence of Omicron, that third theory – linked to viral evolution within immunocompromised hosts – is an area of interest for researchers, with a new study suggesting that monitoring chronic infections may be a way to anticipate future variables that could to pose a threat.
In early results, Published online as a preprint paper Not yet reviewed, a team of Israeli researchers affiliated with Tel Aviv University examined 27 patients with chronic coronavirus.
All of these individuals have suppressed the immune system for various reasons, including some types of cancer, high-dose steroid treatment or low levels of T-cells from conditions such as AIDS.
“It is hypothesized that immune system disorders inhibit virus clearance compared to patients with a healthy immune system, and thus the virus thrives for extended periods of time,” the researchers wrote.
Mutations “reflect” those in the variants of concern
Usually during a SARS-CoV-2 infection, shedding of the virus lasts anywhere from a few days to a few weeks.
But documented cases of chronic infection, such as those the team studied, can last longer, with replication viruses potentially detectable for extended periods of time. (The researchers note that this differs markedly from long-term COVID, where the initial infection is shorter but symptoms persist.)
After analyzing the cohort of patients with chronic infection, the team concluded that the overall patterns of mutations observed in those cases “closely reflect” patterns observed in variants of concern.
There have been cases of viral rebound, for example, in which the virus was reduced to undetectable levels, but then appeared to replicate throughout the body again — potentially indicating mutants capable of evading antibodies, the researchers wrote. , providing a potential signal that scientists can use to identify future variables.
But in a small sample of patients, the team did not find cases of specific mutations that could lead to transmission of the virus, leading the researchers to suggest that any variants seen in chronically infected patients might lack this essential ability. This is a potential trade-off between becoming more transmissible or more immune-evading, they said.
“Overall, we suggest that extensive surveillance of chronic infection can be used to predict the range of mutations in the future [variants of concern]The team concluded.
‘Very important’ studies
These types of studies prove to be “extremely important,” said Jason Kendracchuk, assistant professor of medical microbiology and infectious diseases at the University of Manitoba in Winnipeg, but he stressed that a small subset of patients does not necessarily represent what’s going on most. Widespread with chronic infections.
Kindrachuk said he was not surprised that there were cases of immune evasion in the 27 patients studied, but noted that it would be necessary to understand why there were no mutations associated with increased transmissibility, which helped multiple species spread like wildfire.
“Whether those kinds of shifts in the virus are more random or associated with a subset of chronic infection, it’s going to be important to determine,” he said.
Virologist Angela Rasmussen, who works with the Vaccines and Infectious Diseases Organization of the University of Saskatchewan in Saskatoon, questioned this element, noting that it is difficult to suggest that any trade-offs occur on a larger scale based on a sample of this size.
It indicated that Omicron may have originated within an immunocompromised host and possesses a variety of mutations, making it highly infectious and immunologically elusive, which throws a key to the Israeli team’s conclusions.
“But other than that, I think it’s a very interesting study,” Rasmussen said. “And it definitely adds a lot to our body of knowledge.”
Crucial not to “ostracize” patients
Experts who spoke to CBC News agreed that this latest research, as well as previous findings about viral development in people with chronic conditions with COVID-19, point to the need to monitor those types of patients.
“I think it’s really important to start building networks like this to try to start understanding which mutations are more likely to appear in the case of persistent infection,” Rasmussen said.
This is easier said than done, Kindrachuk said, given that much of Canada is relaxing restrictions and limiting access to testing, while other countries are dealing with uncontrolled transmission.
“How do we treat patients with chronic infection? Not everyone with a chronic infection has some form of anxiety… so what do you do?” Asked.
Kindrachuk said monitoring of these patients is critical, given the need to identify variants and stop their spread.
“If it stays in that person – even if it has all the mutations, it needs to be a better, more suitable version of SARS-CoV-2 – if it stays outside of someone else, it will resolve over time,” he continued.
But Kindrachuk said there is a fine line between monitoring these patients and further marginalizing people who may already be suffering from stigmatizing conditions such as HIV/AIDS.
“We don’t want to ostracize people,” he said.