Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the pathogen responsible for coronavirus disease 2019 (COVID-19), has caused morbidity and mortality at an unprecedented scale globally.
As of February 22, 2022, there have been 424,822,073 confirmed cases of COVID-19, including 5,890,312 deaths, reported to World Health Organization (WHO) although estimates greatly surpass these figures.
Though there is now a reasonably good knowledge on acute COVID-19, much less is known about the persistent or new symptoms following recovery from initial infection.
Really by saying that post-COVID is a new phenomenon, but it is not something that is completely new to medicine. In the 1892, Russian influenza that killed about million people globally, it was widely recognised that survivors of this disease could have persistent neurologic disorders, psychiatric disorders or lingering after-effects.
This was very well documented in their time that people could have psychoses, encephalitis lethargica (fever, headache, double vision, delayed physical and mental response and lethargy) and severe post-viral symptoms.
They were recognised on a wide scale affecting a whole generation. Sir William Osler, father of modern medicine, said “almost every form of disease of the nervous system may follow influenza”.
Most people with COVID-19 return to baseline after acute infection with SARS-CoV-2, and though the recovery time is different for everyone, for many people symptoms will resolve by 12 weeks.
But, a proportion of people report ongoing health issue that experience lingering symptoms for weeks to months following acute SARS-CoV-2 infection, and this condition is variously termed as long COVID, post-COVID condition/syndrome, COVID-19 long-haulers, post-acute sequelae of SARS-COV-2 infection (PASC) and post-acute COVID syndrome (PACS). Post COVID-19 condition refers collectively to the group of long-term symptoms (syndrome) that some people experience after they have had COVID-19.
Post COVID-19 condition can affect a person’s ability – physical as well as mental – to perform daily activities such as work or household chores. Both children and adults can be affected by ongoing symptomatic COVID-19.
Definition
According to WHO, post COVID-19 condition occurs in individuals with a history of probable or confirmed SARS-CoV-2 infection, usually three months from the onset of COVID-19 with symptoms that last for at least 2 months and cannot be explained by an alternative diagnosis.
National Institute for Health and Care Excellence (NICE), UK defines long COVID as signs and symptoms that develop during or after an infection consistent with COVID–19, continue for more than 12 weeks and are not explained by an alternative diagnosis.
In addition, the term ‘long COVID’ is commonly used to describe signs and symptoms that continue or develop after acute COVID–19. It includes both ongoing symptomatic COVID–19 (from 4 to 12 weeks) and post–COVID–19 syndrome (12 weeks or more). Post COVID–19 condition may be considered before 12 weeks while the possibility of an alternative underlying disease is also being.
However, this definition of post COVID-19 condition will likely change as new evidence emerges and our understanding of the consequences of COVID-19 continues to evolve.
Symptoms
Though it remains unknown that how many patients are affected with longer term sequelae after acute COVID-19, published reports indicate that about 10–20 per cent of COVID-19 patients suffer chronic effects. However, some estimates suggest more than 40 per cent suffer chronic effects.
Long COVID or Post COVID-19 condition is a protean disease. Symptoms may be new onset, following initial recovery from an acute COVID-19 episode or persist from the initial illness.
Post-infection follow-up data show that a significant proportion of hospitalised and non-hospitalised patients experience persistent symptoms and organ dysfunction. Some people also experience psychological effects as part of post COVID-19 condition.
There may be something unique about COVID-19 and the way it is a diffuse multisystem disease but it is probably just that we have never seen an infection on this scale in modern times that it is making us recognise that it is a post-viral illness. Studies show that the long-term effects of COVID-19 can affect multiple organ systems, can cause cognitive disturbances and decline in quality of life.
A significant proportion of people that had COVID-19 developed long COVID. The post-acute COVID-19 US study showed 32.6 per cent of patients reported persistent symptoms, including 18.9 per cent with new or worsened symptoms.
Difficulty in breathing (dyspnea) while walking up the stairs (22.9 per cent) was most commonly reported, while other symptoms included cough (15.4 per cent) and persistent loss of taste and/or smell (13.1 per cent).
Another post-acute COVID-19 Italian study reported persistence of symptoms in 87.4 per cent of 143 patients discharged from hospital who recovered from acute COVID-19 at a mean follow-up of 60 days from the onset of the first symptom.
Most commonly reported symptoms include fatigue (53.1 per cent), dyspnea (43.4 per cent), joint pain (27.3 per cent) and chest pain (21.7 per cent), and 55 per cent of patients continuing to experience three or more symptoms.
A decline in quality of life was noted in 44.1 per cent of patients in this study. And a study from France conducted on 50 survivors of non-critical COVID-19 reported persistence of symptoms in two-thirds of individuals at 60 days follow-up. Various studies from the UK, Spain, France and US reported similar findings.
Brain fog: While recovering from COVID-19, some people experience what is called ‘brain fog’. It is not a medical term but used to describe a range of symptoms including thinking more slowly than usual, poor concentration, feeling confused, fuzzy thoughts, forgetfulness, lost words and mental fatigue.
A study published in the month of January 2022 from a post-COVID clinic in New York showed that some 67 per cent of 156 patients were affected by brain fog, and they manifested as problems remembering recent events, coming up with names or words, staying focused, and issues with holding onto and manipulating information, as well as slowed processing speed.
Brain fog is a common after-effect of COVID-19. Symptoms may vary and change over time. It is similar to the effects of sleep deprivation or stress. It is not the same as dementia and does not mean structural damage to the brain. It is not just people who were hospitalised with coronavirus who can develop brain fog. Anxiety, low mood and fatigue all play a role in affecting how the brain functions. People usually recover from brain fog.
Children and adolescents
A person of any age who has had COVID-19 can later develop a post-COVID condition. Although post-COVID conditions appear to be less common in children and adolescents than in adults, long-term effects after COVID-19 do occur in children and adolescents. Studies have reported long-term symptoms in children with both mild and severe COVID-19.
Though the risk of long COVID in children is much lower, researchers stressed the risk to young people is ‘not trivial’, and said it was vital children get the medical support they need.
Similar to the symptoms seen in adults, the most common symptoms reported have been tiredness or fatigue, headache, trouble sleeping (insomnia), trouble concentrating, muscle and joint pain, and cough.
If a child has post-COVID condition that impacts their ability to attend school, complete schoolwork or perform their usual activities, it may be helpful to discuss the issue with the school administrators.
Young children may have trouble describing the problems they are experiencing. Information on post-COVID conditions in children and adolescents is limited. It is possible that other symptoms may be likely in younger age groups.
Mechanisms underlying long COVID
The underlying mechanisms of long COVID is yet to be understood completely. Dr Elaine Maxwell, from the National Institute of Health Research, said that COVID is a ‘complex condition’, there could be a number of different things happening after a COVID-19 infection and an autoimmune response has been one of the suspected mechanisms.
The possible mechanisms include direct toxic effects of the virus on various cells of the body casing damage, immune dysregulation and inflammatory tissue damage.
Predictors and risk factors of long COVID
Researchers have identified several factors that can be measured at the initial point of COVID-19 diagnosis that anticipate if a patient is likely to develop long COVID. These factors are the presence of certain autoantibodies (proteins that body makes against self), pre-existing Type 2 diabetes, SARS-CoV-2 RNA levels in the blood and Epstein-Barr virus DNA levels in blood (reactivation of EBV).
In addition, researchers found that mild cases of COVID-19, not just severe cases, are associated with long COVID. They also suggest that administering antivirals very early in the disease course may potentially prevent some long COVID.
Analysis showed a considerable diversity of reported risk factors including age, sex, comorbidities, ethnicity and severity of the acute phase. Studies showed that long COVID is most common in 35-to-69-year-olds, women, people with underlying conditions that limit their day-to-day activities, those work in health and social care and people living in poorer areas.
Vaccination and long COVID
The observational studies showed that vaccinated people who are subsequently infected with COVID-19 are less likely to report symptoms of long COVID than unvaccinated people. There is also evidence that unvaccinated people with long COVID who were subsequently vaccinated had, on average, reduced long COVID symptoms (though some people reported worsened symptoms after vaccination), and also reported fewer long COVID symptoms than those who remained unvaccinated.
Conclusion
Long COVID is a complex, multifactorial illness that describes the residual effects of acute COVID-19 infection. While most persons with COVID-19 recover and return to normal health, some patients can have symptoms that can last for weeks or even months after recovery from acute illness.
A whole host of symptoms can occur in patients after they had COVID, and it usually presents with clusters of symptoms, often overlapping, which can fluctuate and change over time and can affect any system in the body. A person of any age who has had COVID-19 can later develop a post-COVID condition including children and adolescents.
Long COVID is causing significant morbidity in survivors of COVID-19, yet the pathobiology is poorly understood. The likelihood of developing ongoing symptomatic covid-19 or post-covid-19 syndrome is not thought to be linked to the severity of their acute covid-19, that is even people who are not hospitalised and who have mild illness can experience persistent or late symptoms. If new or ongoing symptoms occur, they can change unpredictably affecting people in different ways at different times.
The closing message: The truth is that long COVID/post COVID-19 condition has a serious impact on people’s ability to return to work, affecting the mental, social sphere and with economic consequences for them, their families and society.
The best way to prevent post-COVID conditions is to prevent COVID-19 illness. For people who are eligible, getting vaccinated against COVID-19 is the best way to prevent getting COVID-19, and in addition, evidence shows that vaccines also provide protection against long COVID.
- Dr Sivaselvam Sivakumar is the laboratory head and consultant pathologist at Oceania Hospitals Pte Ltd. The views expressed are his and not of this newspaper.
