For most people, infection with SARS-CoV-2 (the virus that causes COVID-19) causes mild short-term symptoms, acute respiratory illness, or possibly no symptoms. But there are people who show long-lasting symptoms after infection; this has been called “long COVID”.
Scientists have been researching COVID for a long time. It is not well understood, although our knowledge about it is growing. Here I take a look at what we have learned so far: who is at risk, how often it is and what its effects are.
When defining who is at risk for a long COVID and the mechanisms involved, we can reveal appropriate treatments to test them or whether the measures taken at the beginning of the disease could improve it.
Wide vulnerability
Long COVID is characterized by a constellation of symptoms, which include – variably – difficulty breathing, marked fatigue, headache and loss of ability to taste and smell normally.
A relatively large study of 384 individuals sick enough to be hospitalized with COVID-19 showed that 53% remained breathless in a follow-up assessment one or two months later, with 34% coughing and 69% reported fatigue.
In fact, early analysis of self-reported data presented through the COVID Symptom Study app suggests that 13% of people experiencing COVID-19 symptoms have it for more than 28 days, while 4% have symptoms. after more than 56 days.
It is perhaps not surprising that people with more severe illnesses initially, characterized by more than five symptoms, appear to have an increased risk of long-term covid. Old age and being women also seem to be risk factors for having prolonged symptoms, as does having a higher body mass index.
Those who use the application are usually in the most appropriate area of the population, with an interest in health. It is therefore surprising that such a high proportion have symptoms one or two months after the initial infection. In general, these are not highly vulnerable people to COVID-19.
Another initial research (pending peer review) suggests that SARS-CoV-2 could also have a long-term impact on people’s organs. But the profile of those affected in this study is different from those who show symptoms through application.
This research, which examined a sample of 200 patients who had recovered from COVID-19, found mild organ damage in 32% of people’s hearts, 33% of people’s lungs, and 12%. of people’s kidneys. Multiple organ damage was found in 25 percent of patients.
The patients in this study had a mean age of 44 years, so they were part of the young working-age population. Only 18% had been hospitalized with COVID-19, which means that organ damage can occur even after a non-serious infection. Having a disease that leads to more severe COVID-19, such as type 2 diabetes and ischemic heart disease, was also not a prerequisite for organ damage.
Find out what’s going on
There are many reasons why people may have symptoms months after a viral illness during a pandemic. But getting to the bottom of what happens to people will be easier for some parts of the body than for others.
When symptoms point to a specific organ, investigating is relatively straightforward. Doctors can examine the electrical flow around the heart if someone suffers from palpitations. Or they can study lung function (tissue elasticity and gas exchange), where shortness of breath is the predominant symptom.
To determine if kidney function has deteriorated, the components of a patient’s blood plasma are compared to those of urine to measure how the kidneys filter waste.
Rather more difficult to explore is the symptom of fatigue. Another recent large-scale study has shown that this symptom is common after COVID-19 (which occurs in more than half of cases) and appears to be unrelated to the severity of early disease.
In addition, tests showed that the people examined did not have high levels of inflammation, suggesting that fatigue was not caused by the continuation of the infection or by their immune system working overtime.
Risk factors for long-term symptoms in this study included being a woman (according to the COVID Symptom App study) and, interestingly, having a previous diagnosis of anxiety and depression.
Although men have a higher risk of serious infection, it seems that women are more affected by long COVID may reflect their different or changing hormonal status. The ACE2 receptor that SARS-CoV-2 uses to infect the body is present not only on the surface of respiratory cells, but also in the cells of many hormone-producing organs, including the thyroid, adrenal gland. and the ovaries.
Some symptoms of long COVID overlap with menopausal symptoms and hormone replacement by medications may be a way to reduce the impact of symptoms. However, clinical trials will be essential to accurately determine whether this approach is both safe and effective. Applications have been submitted to initiate this investigation.
With so many things that have happened over the last year, we will have to separate the impacts from the virus itself and those that could be the consequence of the massive social disruption caused by this pandemic.
What is clear, however, is that long-term symptoms after COVID-19 are common and that the causes and treatments of COVID will probably need to be investigated long after the outbreak itself has subsided.
Frances Williams, Professor of Genomic Epidemiology and Rheumatologist Consultant at King’s College London.
This article is republished from The Conversation under a Creative Commons license. Read the original article.