Long COVID, affecting 5-10% of COVID-19 patients, might be caused by the enduring presence of the virus in the body.
Research suggests that viral fragments, possibly live, linger and lead to symptoms. Addressing this involves antiviral treatments, enhanced public awareness, and preventive measures against reinfection.
Understanding Long COVID and Its Prevalence
About 5–10% of people infected with COVID-19 develop long COVID, experiencing symptoms that last three months or longer.
Scientists have suggested several biological mechanisms to explain long COVID. However, in a recent perspective article in the Medical Journal of Australia, we propose that long COVID may largely be caused by the virus itself persisting in the body.
Since the early days of the pandemic, researchers have recognized that SARS-CoV-2 — or its remnants — can remain in different tissues and organs long after the initial infection. This phenomenon is referred to as "viral persistence."
Credit: SciTechDaily.com
Evidence of Persistent Virus and Its Implications
While the long-term presence of residual viral fragments in some people's bodies is now well established, what remains less certain is whether live virus itself, not just old bits of virus, is lingering – and if so, whether this is what causes long COVID. This distinction is crucial because live virus can be targeted by specific antiviral approaches in ways that "dead" viral fragments cannot.
Viral persistence has two significant implications:
- when it occurs in some highly immunocompromised people, it is thought 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 beyond the acute illness. In other words, long COVID could be caused by a long infection.
Current Research Findings on Viral Persistence
While there remains no single study that confirms that persistent virus is the cause of long COVID, collectively several recent key papers make a compelling case.
In February, a study in Nature found a high number of people with mild COVID symptoms had extended periods of shedding the genetic material of the virus, so-called viral RNA, from their respiratory tract. Those with persistent shedding of this viral RNA – which almost certainly represents the presence of live virus – were at higher risk of long COVID.
Other key papers detected replicating viral RNA and proteins in blood fluid of patients years after their initial infection, a sign that the virus is likely replicating for long periods in some hidden reservoirs in the body, perhaps including blood cells.
Another study detected viral RNA in ten different tissue sites and blood samples 1–4 months after acute infection. This study found the risk of long COVID (measured four months following infection) was higher in those with persistently positive viral RNA.
The same study also gave clues about where in the body the persisting virus resides. The gastrointestinal tract is one site of considerable interest as a long-term viral hideout.
The Challenge of Proving Viral Replication
Earlier this month, further evidence of persistent virus increasing likelihood of long COVID has been published as part of the RECOVER initiative, a collaborative research project that aims to address the impacts of long COVID.
However, formal proof that virus capable of replicating can last for years in the body remains elusive. This is because isolating the live virus from reservoirs inside the body where the virus "hides" is technically challenging.
In its absence, we and other scientists argue the cumulative evidence is now sufficiently compelling to galvanise action.
Strategies to Address Long COVID
The obvious response to this is to fast-track trials of known antivirals for prevention and cure of long COVID.
This should include more left-field therapies such as the diabetes drug metformin. This has possible dual benefits in the context of long COVID:
- its antiviral properties, which have demonstrated surprising efficacy against long COVID
- as a potential therapeutic in treating impairments related to fatigue.
However, another major thrust 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 these into forms usable in the clinic is a large hurdle that requires support and investment from governments.
Raising Awareness and Preventing Long COVID
The notion of "long infection" as a contributor or even the driver of long COVID is a powerful message. It could help demystify the condition in the eyes of the wider community and increase awareness among the general public as well as medical professionals.
It should help raise awareness in the community of the importance of reducing rates of re-infection. It is not just your first infection, but each subsequent COVID infection carries a risk of long COVID.
Long COVID is common and isn't restricted to those at high risk of severe acute disease but affects all age groups. In one study, the highest impact was in those aged 30 to 49 years.
Preventive Measures and Future Outlook
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 conscious of the importance of well-ventilated indoor spaces, opening the windows and improving airflow as COVID spreads through air. More sophisticated ways of ensuring indoor air is safe involve monitoring quality and filtering air in spaces that cannot be easily naturally ventilated
- using high-quality masks (that are well-fitting and don't let air in easily, such as N95-type masks) in settings where you don't have confidence of the quality of the indoor air and/or that are crowded
- testing, so you know when you're positive. Then, if you're eligible, you can get treatment. And you can be vigilant about protecting those around you with masks, staying at home where possible, and ventilating spaces
- staying up to date with COVID booster doses. Vaccines reduce long 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 clinicians to take patients more seriously as they attempt to access the treatments and services that already exist.
Written by:
- Brendan Crabb, Director and CEO, Burnet Institute
- Gabriela Khoury, Theme Leader, Antiviral Immunity, Burnet Institute
- Michelle Scoullar, Senior Research Fellow, Burnet Institute
Adapted from an article originally published in The Conversation.
News
A Single Enzyme Could Hold the Key to Treating a Devastating Brain Disorder
Blocking an enzyme’s production restored brain growth and healthy behaviors in mice engineered to develop Angelman syndrome, pointing to a possible treatment target. Children with Angelman syndrome begin to show difficulties with thinking and [...]
Scientists Develop a Clever New Way To Kill Cancer Cells From the Inside
Scientists have developed an experimental strategy that exploits a chemical byproduct of cancer cells to produce anticancer drugs directly inside them. Scientists in Japan have developed an experimental method that uses a chemical produced [...]
Our books are available worldwide!
Online Sellers other than Amazon, Routledge, and IOPP Indigo Global Health Care Equivalency in the Age of Nanotechnology, Nanomedicine and Artifcial Intelligence Global Health Care Equivalency In The Age Of Nanotechnology, Nanomedicine And Artificial [...]
After only a short training, people in a coma managed to send targeted signals
Researchers have succeeded in communicating with brain-injured patients who are unconscious. They see enormous potential in this for future treatments. Patients who lie motionless in bed after a severe brain injury and do not [...]
MIT Scientists Reprogram Immune Cells Inside the Body To Destroy Cancer
Natural killer cells reprogrammed inside mice eliminated lymphoma tumors and helped damaged livers heal, though whether this approach could help people with cancer or autoimmune disease remains unknown. To make a cancer treatment from [...]
Melanoma mRNA Vaccine Shows Promise in Preventing Disease Recurrence
Key takeaways: Phase 3 trial finds personalized intismeran plus pembrolizumab may better prevent high-risk melanoma recurrence after surgery The trial enrolled 1,137 patients and builds on phase 2 results showing about half the recurrence [...]
Scientists Discover a Powerful New Weapon Against a Dangerous Gut Infection
The promise of an experimental treatment for C. difficile gut infections lies partly in the bacteria it leaves alive, according to early laboratory and mouse research. Broad-spectrum antibiotics can disrupt the gut’s microbial community, [...]
Your Bones May Hold a Hidden Clue to Blood Cancer Survival
For people with blood cancers called myelodysplastic syndromes, osteoporosis may hold an overlooked clue to survival, a three-year observational study suggests. In blood cancers that develop in the bone marrow, an important clue to [...]
Researchers Discover What Reading for Pleasure May Be Doing to Your Brain
Reading for pleasure may offer surprising benefits for the brain, with research linking the habit to better mental health, stronger cognitive abilities, and a lower risk of dementia. Reading for pleasure may do far [...]
Scientists Discover a Hidden Trigger That Keeps Inflammation Alive
Inflammation persists after proteins detach from immune receptors, revealing a potential target for autoimmune treatments. Since a Nobel Prize-winning discovery in the 1990s identified molecules called Toll-like Receptors as the guardians of the human [...]
A Virus Gives Itself Away the Moment It Attacks
Researchers have found the trigger behind a powerful bacterial defense against viruses. Viruses that prey on bacteria could become an increasingly important tool for treating bacterial infections, particularly as antibiotic resistance makes some infections [...]
Scientists Discover Aspirin May Slash Dementia Risk by 70% – but Only for Certain People
Aspirin was linked to a sharply lower dementia risk in some older adults, and their genes may hold the clue. A Monash University analysis found that older adults with a particular genetic profile had [...]
Inflammation May Awaken Dormant Cancer Cells Years After Treatment
The body’s response to inflammation may disturb cancer cells that have been lying silent for years, giving them an opportunity to grow again. Researchers at the Francis Crick Institute have found that gut inflammation [...]
Where do nanoparticles go once they enter the body?
New international best practice guidance, co-written at ANSTO, sets out how to measure where nanoparticles like titanium dioxide end up in the body and how long they remain. The guidance has been shared by [...]
Long-Acting HIV Shots Could Solve a Major Treatment Challenge for Young People
A major African trial suggests that changing how HIV treatment is delivered could significantly improve viral suppression in adolescents. Young people with HIV were more likely to keep the virus suppressed when they received [...]
WHO Factsheets – The top 10 causes of death
In 2023, the 10 leading causes of death accounted for 33 million deaths, or 54% of the total 61 million deaths worldwide. The top global causes of death, in order of total number of lives lost, [...]
