About 5-10% of people with COVID infection experience long-term COVID, with symptoms lasting three months or longer.
Researchers have proposed several biological mechanisms to explain long COVID. However, in a perspective article published in the latest Medical Journal of Australia, we argue that much, if not all, of COVID appears to be caused by the virus itself persisting in the body.
Since relatively early in the pandemic, it has been recognized that SARS-CoV-2 – or at least remnants of the virus – can remain in various tissues and organs for extended periods of time in some people. This theory is known as 'viral persistence'.
Although the presence of long-term residual virus fragments in some people's bodies has now been clearly established, it remains less certain whether the live virus itself, and not just old bits of virus, is sticking around – and if so, whether this is the cause is from prolonged COVID-19 attacks. . This distinction is crucial because live viruses can be targeted by specific antiviral approaches in ways that “dead” viral fragments cannot.
Viral persistence has two important implications:
when it occurs in some people with severely weakened immune systems, it is believed to be the source of new and substantially different-looking variants, such as JN.1
it has the potential to continue to cause symptoms in many people in the wider population long after the acute illness. In other words, long COVID-19 can be caused by a long-term infection.
What does the research say?
While there is no single study confirming that a persistent virus is the cause of long COVID, several recent key papers together make a compelling argument.
In February, a study in Nature found that a large number of people with mild COVID symptoms had extended periods of shedding the virus's genetic material, called viral RNA, from their airways. Those with sustained release of this viral RNA – which almost certainly represents the presence of a live virus – were at greater risk for long-term COVID.
Other key papers discovered replicating viral RNA and proteins in patients' blood fluid years after their initial infection, a sign that the virus is likely replicating for long periods in some hidden reservoirs in the body, possibly including blood cells.
Another study detected viral RNA in ten different tissue sites and blood samples 1 to 4 months after the acute infection. This study found that the risk of long-term COVID (measured four months after infection) was higher in people with persistently positive viral RNA.
The same study also provided clues as to where in the body the persistent virus is located. The gastrointestinal tract is a site of significant importance as a long-term refuge for viruses.
Earlier this week, further evidence that persistent viruses increase the risk of long COVID was published as part of the RECOVER initiative, a joint research project that aims to tackle the impact of long COVID.
However, formal proof that a virus that can reproduce can persist in the body for years remains elusive. This is because isolating the live virus from reservoirs in the body where the virus “hides” is technically challenging.
Failing that, we and other scientists argue that the cumulative evidence is now sufficiently compelling to spur action.
What should happen next?
The obvious answer to this is to accelerate trials of known antiviral drugs for the prevention and cure of long-term COVID.
This should include more left-field therapies such as the diabetes drug metformin. This has potential dual benefits in the context of long COVID:
its antiviral properties, which have shown surprising efficacy against long-term COVID
as a potential therapeutic agent in the treatment of fatigue-related disorders.
However, another important impetus should be the development of new drugs and the establishment of clinical trial platforms for rapid testing.
Science has uncovered exciting therapeutic options. But translating this into forms usable in the clinic is a major hurdle that requires support and investment from governments.
Demystify and prevent long COVID
The idea of a “long infection” as a contributor or even driver of long COVID-19 is a powerful message. It could help demystify the condition in the eyes of the broader community and raise awareness among the general public and medical professionals.
It should help raise awareness in the community of the importance of reducing reinfection rates. It's not just your first infection, but with each subsequent COVID infection there is a risk of long-term COVID.
Long COVID-19 is common and is not limited to people at high risk of severe acute illness, but affects all age groups. In one study, the greatest impact was seen in people aged 30 to 49.
So for now, we all need to reduce our exposure to the virus with the tools available, a combination of:
clean indoor air approaches. In its simplest form, this means being aware of the importance of well-ventilated indoor spaces, opening the windows and improving airflow as COVID spreads through the air. More advanced ways to ensure indoor air is safe include monitoring quality and filtering air in areas that cannot be easily ventilated naturally
the use of high-quality masks (that fit well and do not easily let in air, such as N95 masks) in environments where you are not confident in the quality of the indoor air and/or where it is crowded
testing so you know when you are positive. If you qualify, you can then receive treatment. And you can be vigilant by protecting those around you with masks, staying home where possible, and ventilating spaces
staying up to date on COVID booster doses. Vaccines reduce long-term COVID and other post-COVID complications.
Hopefully one day there will be better treatments and even a cure for long COVID. But in the meantime, increased awareness of the biomedical basis of long COVID should prompt physicians to take patients more seriously as they try to access the treatments and services that already exist.
(Authors: Brendan Crabb, Director and CEO, Burnet Institute, Gabriela Khoury, Theme Leader, Antiviral Immunity, Burnet Institute, Michelle Scoullar, Senior Research Fellow, Burnet Institute)
(Disclosure Statement: Brendan Crabb and the institute he leads receive research grants from the National Health & Medical Research Council of Australia, the Medical Research Future Fund, DFAT's Center for Health Security and other Australian federal and Victorian state government agencies. He is chairman of the Australian Global Health Alliance and the Pacific Friends of Global Health, both in an honorary position. And he serves on the board of the Kids Research Institute Australia, on advisory committees of mRNA Victoria, the Sanger Institute (UK), The Brain Cancer Center (Australia), and is a member of OzSAGE and The John Snow Project, all honorary positions.
Gabriela Khoury receives funding from the Medical Research Future Fund.
Michelle Scoular receives funding from the Medical Research Future Fund. She is affiliated with Kliniek Nineteen, a clinic that specializes in long COVID.)
This article is republished from The Conversation under a Creative Commons license. Read the original article.
(This story has not been edited by DailyExpertNews staff and is auto-generated from a syndicated feed.)
