Long Covid as a multi-system disease: What the research tells us

This week’s blog is written by Dr Elisa Perego MA PhD (@elisaperego78), a patient and a researcher, who is affiliated as an Honorary Research Fellow to University College London and a Long Covid Kids champion.

Long Covid is a multi-system, heterogeneous disease. As a disease entity, Long Covid can basically affect all systems and organs in the body. This does not mean everyone with Long Covid will have proven pathology in every organ – but that damage, across different patient groups, can appear, basically, everywhere in the body. Some people will have physical damage documented only in one organ. Others will have physical impairment and biological abnormalities documented in many organs and body systems. Persistence of SARS-CoV-2 – or parts of it – in various body tissues is increasingly documented in the scientific literature.

Many people, unfortunately, do not have access to the best biomedical tests, like very sophisticated scans and bloodwork. Some of these tests may be available only in a research setting, such as a university study. And there are limits to what even some of the best tests can show. A lot of damage from Covid was initially discovered in deceased patients, on autopsy. Many people may not have proven evidence of all the biological damage they suffered from SARS-CoV-2 infection. They do report, however, symptoms and signs affecting several parts of their bodies and their daily lives. The best possible medical care and other support services, like paid sick leave and disability, should be available to everyone suffering from Long Covid, regardless of access to the most sophisticated tests. Standard tests can come back “clean” but this shouldn’t invalidate people’s experience and suffering.

There are thousands of scientific publications that show damage from Covid–Long Covid spanning across many organs and body systems, the:

No part of the body seems spared. A search on the repository for biomedical literature PubMed, carried out on 18 March 2023, under *Covid, leads to over 341,000 results. Covid is one of the most studied diseases in medical history, especially if we consider it has been around for a very short time period compared to other common diseases.

The cardiovascular system is one of the most affected systems in the body. We know Covid can damage or affect the heart and blood vessels. Covid can contribute to severe clotting abnormalities , which can persist or become evident long after infection [Wang et al. 2022]. Cardiovascular disease and clotting problems in acute and Long Covid are particularly worrisome. A reason why is because clinical events, such as pulmonary embolism, stroke, or myocardial infarction, are immediately life-threatening.

There is also evidence that Covid can affect the human reproductive systems: problems such as erectile dysfunction and ovarian  injury have been documented after Covid and discussed in relation to SARS-CoV-2 infection. Covid–Long Covid has also been linked to metabolic  disorders, hyperglycaemia, dyslipidaemia, autoimmunity, and various manifestations seen in other conditions associated with infections like ME/CFS.

Long Covid can present with a relapsing-remitting pattern, a progression over time, and delayed life-threatening events far from infection [Munblit et al. 2022] . We need further research to fully appreciate the range of severity and subclinical pathology in Covid–Long Covid. Some pathology in Covid–Long Covid has been reported to be asymptomatic (“silent”); accompanied by “mild” symptoms; or by generic symptoms like “fatigue” [Perego et al. 2020].

This is not surprising. Even diseases which can be fatal if not treated – like colorectal cancer or HIV infection – can present initially with no apparent symptoms, or “mild” symptoms. People who have been infected with SARS-CoV-2 deserve accurate information about the potential long-term damage from this infection. They also deserve appropriate medical scrutiny for the vast pulmonary and extrapulmonary manifestations of Covid–Long Covid.

We must remain vigilant against SARS-CoV-2. Vaccination is a tool, but it is not, for now, perfect. Not everyone in the world is vaccinated or boosted. We have known for long you can be infected with SARS-CoV-2 even if you are vaccinated or had Covid before: Omicron, for example, has been under intense scrutiny in this regard [Willet et al. 2022]. Each infection is like playing Russian roulette. Damage to the human body could accumulate over time. Reinfections are not benign. They deserve much more study. Some people may die on reinfection. Reinfections are increasingly being reported. A growing concern is that some could suffer severe Covid or develop Long Covid even if their first infection was apparently uneventful or resolved: we need much more research in this regard to elucidate disease pathways and mechanisms. We have also data from the Long Covid patient community, charities, and support groups, which show people with Long Covid can suffer a setback after reinfection. As I am writing this piece in February–March 2023, as a patient and a researcher, the Covid emergency is far from over.

Disclaimer: This blog is not supposed to be clinical advice, but a brief overview of some mechanisms involved in the long-term  manifestations of SARS-CoV-2 infection–Covid, including potential risks associated with reinfections and lack of appropriate clinical evaluation. It was not possible to discuss the full extent of Covid sequelae and delayed complications in this short piece. This piece is not peer-reviewed.

Author: Alison Twycross PhD RN

Chair - Supporting Healthcare Heroes UK; Editor-in-Chief - Evidence Based Nursing; Former Deputy Dean and Professor of Children’s Nursing

One thought on “Long Covid as a multi-system disease: What the research tells us”

  1. I too suffered from Covid-19 (delta in April 21) , had bouts of Brain fog, unstable gait and issues in concentration/ focus.
    Kept track of results from related Researches. & Took help of “deep breathing & few yoga exercises”
    These helped me a lot.
    Now, near normal.

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