The COVID-19 pandemic continues its endless parade around the world, with virus variants and their sub-lineages still ramping up, while fresh spikes surprise with changes in protein outfits and other antigen accessories. While face masks and vaccines attempt to slow the epidemic and reduce deaths, there is concern about survivors who are manifesting the long-term effects of infection, even after the initial acute phase has subsided.
This phenomenon, known as Long Covid, has been observed since the early 2020 waves and continues with the 2021 variants. How long this pain persists with Omicron family variants still needs to be assessed, as the initial disease caused by them has been reported to be less severe. This may be because the virus has reduced its virulence or its effects have been blunted by immunity acquired from prior infection or vaccination. In any case, the risk of long covid appears to be lower with Omicron than with earlier forms of the virus.
The definition of Long Covid has taken time to evolve. The World Health Organization (WHO) defines it as symptoms due to COVID that appear three months after an acute infection. According to the WHO, “Post-Covid-19 conditions occur in individuals who have a history of probable or confirmed SARS-CoV-2 infection, usually three months after the onset of COVID-19 with symptoms that are at least Lasts less than two months and may not be. Explained by an alternative diagnosis.” The Centers for Disease Control (CDC), USA, considers symptoms lasting more than four weeks after acute illness as a sign of prolonged COVID. UK National Health Service (NHS) subset classified as ‘ongoing symptomatic COVID-19’ (4-12 weeks) and ‘post-COVID-19 syndrome’ (more than 12 weeks).
Scientific reports published from around the world differ in their estimates of the long COVID, depending on which criteria they use. A recent analysis of millions of health records by the CDC estimated 20 percent of this suffering among COVID survivors. It may have been missed by those who could or could not access healthcare for various reasons. An earlier household survey reported by the CDC in June this year identified the rate as one in three individuals. A meta-analysis of global data collected from several studies, published in March 2022, puts the prevalence of chronic covid in close to 50 percent of all survivors. Whatever the actual percentage, the total number is a matter of great concern as the health and well-being of a large number of COVID survivors have been compromised.
The long-term health effects of COVID may result from one or more of the following: (1) the effects of organ damage directly caused by the virus; (2) the residual effect of injury caused by the vigorous immunological response exerted by the body when combating the virus; (3) the progression of other health conditions associated with COVID-triggered inflammation, particularly diabetes; (4) Neglect of other health conditions by medical care focused solely on COVID management; (5) Side effects of drugs and technologies used for COVID care, such as steroids and intensive care-induced psychological stress. The reactivation of a latent infection with the Epstein-Barr virus has also been considered as a cause of long covid.
Since chronic fatigue has been seen with some other viral infections, and long-term illness has also been seen with SARS-1 and MERS-related coronaviruses, the majority of long-term covids appears to be related to interactions between the virus and the human body. . , The initial tendency of doctors to dismiss the complaints of COVID victims as purely psychological has proved to be a false and unfair assessment.
Several clinical features of Long COVID have been described, including diseases of various organs – from the brain and heart to the gastrointestinal system and pancreas. In addition to direct tissue damage caused by the virus, there is some evidence to suggest that the tenth cranial nerve (the vagus) may be affected. It is the longest cranial nerve, so named because it is the ‘wanderer’ that courses from the brain to the chest and abdomen to innervate and control many vital organs.
While many organs and body functions can be affected by long-term covid, its effects on the heart and blood vessels have attracted considerable attention. Inflammation of the heart muscle (‘myocarditis’) can result from damage to muscle fibers either by direct effects of the virus or as a result of immunological injury caused by the body’s own defenses. The pericardium, the membrane covering the heart, may also become inflamed (‘pericarditis’). Heart muscle damage has been detected in people who have died of COVID. In survivors, evidence of cardiac involvement was associated with increased blood levels of enzymes released by the damaged heart muscle, a decrease in the pumping capacity of the heart muscle as noted by echocardiography or radionuclide imaging, and muscle fiber damage as seen by magnetic resonance imaging. comes from proof. MRI). Impaired heart function is reflected in symptoms of fatigue, decreased exercise tolerance, and deep heartburn, although clinical signs of heart failure are rare in individuals with pre-existing heart disease.
Determining the incidence of cardiac involvement in COVID is difficult as only a section of COVID survivors can be comprehensively assessed. In the pre-Omicron era, Valentina Puntmann in Frankfurt studied 100 consecutive patients about 10 weeks after testing positive for the virus. He did cardiac MRI with gadolinium contrast agent. They observed cardiac abnormalities in three of the four patients. Findings included increased pumping action of the heart, inflammation or fibrosis of the heart muscle, and pericarditis. Most patients recover in six months, although symptoms may last for a few years to a year.
Heartbeat abnormalities may also occur. The vagus nerve, which has a slowing effect on the heart rate, usually controls the heartbeat. With that inhibitory effect gone and a stressed body pumping out adrenaline and other catecholamines, the heart can start racing madly. It can enlarge when a person stands up — a condition called postural orthostatic tachycardia syndrome (POTS). In this disease, within 10 minutes of standing, the heart rate increases to more than 30 beats in adults and more than 40 beats in children. There may also be an irregularity of the heartbeat (‘missed beats’ or ‘arrhythmias’).
When the lungs are affected by covid, the heart can also get stressed. Fibrosis of the lungs creates greater resistance to the heart when it pumps blood to them and the damaged lungs also do not efficiently oxygenate the blood returning to the heart. Blood clots formed due to damaged blood vessels in the acute phase of COVID may dislodge later when the person is active. When clots from the veins travel to the blood vessels of the lungs (‘pulmonary embolism’), they can cause severe circulatory collapse. Because of the greater tendency for blood vessels to become damaged and clot, Covid survivors are at a higher risk of heart attack even a year after the initial infection.
The inner layer of blood vessels (endothelium) is a dynamic structure that responds to changing conditions of blood flow requirements, allowing the artery to dilate or constrict while maintaining blood pressure in a desirable range. COVID has led to endothelial dysfunction, which results in the loss of the ability of blood vessels to dilate when needed. This can lead to high blood pressure, accelerated atherosclerosis and heart attack. COVID has also been observed to increase the risk of long-term erectile dysfunction in men due to the loss of endothelial vasodilatation in the blood vessels of the male genitalia.
While many disorders of the heart and blood vessels have been observed in Long COVID, there is no need to fear that most survivors of COVID will experience them or that their effects will be permanent. Many individuals who manifest the effects of covid for a long time recover over time, especially if the initial infection was mild and there is no re-infection. The time taken to recover will vary depending on the severity of the initial infection, the age of the person, and associated co-morbidities. As advised, it is best to avoid the risk of infection by wearing a mask and getting vaccinated to avoid serious illness that can set the stage for a long COVID. There is no specific treatment available yet but the study of long covid is still an emerging area. As of now, the best preventive advice is to ‘mask up’ and ‘get vaccinated’.
(Prof. K. Srinath Reddy, a Cardiologist and Epidemiologist, is the Chairman of the Public Health Foundation of India (PHFI). Views expressed are personal)