Covid-19: Some long-term effects

 

2021/06/21

 

Many are quite familiar with the acute-stage phenomena in COVID-19. These include the features of any viral infection, together with specific involvement of the respiratory system, as well as other organs. Yet for all that, it was assumed during the initial stages of the pandemic that if one managed to survive an attack by the SARS-CoV-2 virus, one would bounce back into good health fairly soon. This was thought to apply to the entire spectrum of COVID-19, ranging from asymptomatic persons to those who were very severely affected.

However, with the continuous flow of research information during the last 18 months, we have had to change our perspectives. Early on in the pandemic, Chinese and Italian research delineated the prevalence of long-lasting symptoms following apparent recovery among patients admitted to hospital with COVID-19. Following that, a wide variety of sources have contributed to our understanding of persistent health problems experienced by some COVID-19 survivors. Even patients categorised as having mild COVID-19 and were not hospitalized, have had ongoing long-term health effects. They have even formed online groups, such as the Body Politic COVID-19 Support Group, and have also launched patient-led research ventures. These have undoubtedly facilitated scientific recognition of the phenomenon of persistent health problems among COVID-19 survivors and led to recognition of the newly-coined term ‘Long COVID’.

In fact, a plethora of health problems have been reported as sequelae of COVID-19. The specific health effects people experience and composite names for those effects are still being defined. In addition to “Long COVID”, other names given are “Post-COVID-19 Syndrome”, “Long-term COVID” and “Chronic COVID Syndrome”. Furthermore, people who experience ongoing health problems after COVID-19 have been referred to as “Long haulers”. The National Institutes of Health of the US has funded research on health effects that persist after COVID-19 and suggested that while these effects are still being defined, they may collectively be referred to as “Post-Acute Sequelae of SARS-CoV-2 infection” (PASC).

Before describing what PASC covers, it is useful to review the goings-on during acute infection with SARS-CoV-2 in COVID-19. At the onset, the virus vigorously replicates leading to increasing numbers of viral particles in the body. Then onwards and particularly during the latter stages of the infection, the immune system of the body clears the virus. Symptoms can be caused both by direct effects of the virus as well as an overactive immune response. The virus typically infects the respiratory tract and causes respiratory symptoms such as cough and difficulties in breathing. The term “Severe COVID-19” is used to delineate cases of acute infection when lung function has been compromised. However, many other organs too can be affected by the virus and the range of symptoms people with COVID-19 experience varies widely. Many of those who are infected may be asymptomatic, but now it is known that they too can develop PASC.

A very large percentage of people recover from acute COVID-19 within weeks. The time taken for recovery may be longer in more severe cases. There is no consensus, at least not as yet, on where to draw the line between when COVID-19 ends and PASC begins. Various time progressions have been proposed but none of them are finite and written in stone. Simply stated, many guidelines define “Acute COVID-19” as lasting up to four weeks after diagnosis; “On-going COVID-19” as lasting from 4 to 12 weeks after diagnosis, and “Post-COVID-19 Syndrome” as lasting for more than 12 weeks. However, there is increasing recognition that progression of PASC may be non-linear and new symptoms arise after acute illness has resolved or even when other symptoms dissipate. The variable timelines, together with the relatively shorter duration of many research studies have restricted our understanding of PASC.

Long-term symptoms in COVID-19 survivors may be similar or different to what was experienced during the acute illness. Symptoms affecting nearly every part of the body have been reported. One research endeavour identified as many as 55 long-term effects associated with COVID-19. The five most commonly reported symptoms were fatigue (58%), headache (44%), difficulty concentrating; sometimes called “brain fog” (27%), hair loss (25%), and shortness of breath (24%). The long-term effects reported use some medical terms such as “ageusia” (loss of taste), “dyspnoea” (shortness of breath) and “polypnoea” (rapid breathing). To compound matters further, reported symptoms are not just physical. In a study of more than 230,000 COVID-19 survivors, 13% received a new neurologic or psychiatric diagnosis within the first six months after diagnosis.

As doctors and scientists learn more, an early step taken to help better define PASC has been to group together the wide range of symptoms experienced by COVID-19 survivors into distinct syndromes; a syndrome being a collection of symptoms that tend to occur together. At least one definitive syndrome has been defined under the PASC umbrella.

Investigation into cases of children who were hospitalized with an overactive immune-inflammatory or hyperinflammatory syndrome which presented sometime later after the acute infection led to the recognition of what was named as the Multisystem Inflammatory Syndrome or MIS-C. People with this syndrome are under 21 years of age and have multiple organs affected and require hospitalization, some being critically ill. There is now recognition of a similar syndrome among adults; Multisystem Inflammatory Syndrome in Adults or MIS-A. The incidence of both MIS-C and MIS-A are very low. From March 1 through March 10, 2020, the incidence of MIS-C in New York State among people younger than 21 years was 2 per 100,000 individuals, whereas the incidence of COVID-19 was 322 per 100,000 individuals. As of 3rd May 2021, 3,742 cases of MIS-C had been reported in the United States.

While scientists and researchers are trying to define PASC better, they are also trying hard to understand what may be causing the symptoms. Many theories on causation have been put forward. The two leading hypotheses are that symptoms arise from direct tissue damage due to the SARS-CoV-2 virus or from the immune response during acute infection. Another one is that health effects are caused by an ongoing immune response that is practically going inappropriately berserk.

It is difficult to quantify and characterize risk factors for a condition that is not yet all that well defined. It is likely that the risk factors for specific sequelae under the PASC umbrella vary, especially if different sequelae have different causes. Studies conducted to date suggest that four groups of people may be more likely to experience PASC: people with more severe acute illness, those who have underlying unrelated diseases or comorbidities, older adults, and women.

In a nut-shell, most people with COVID-19 fully recover within weeks of the onset of their illness. But for some, the resolution of the acute infection is not the end of their COVID-19 voyage. Some COVID-19 survivors have experienced new, returning, or ongoing, health problems, that persist long after the acute illness. As of 1st of June 2021, there have been more than 170 million cases of COVID-19 reported worldwide. The true number of infections is much higher, possibly more than one billion. If even only a small proportion of those infected develop long-term sequelae, it would create a major public health challenge. We need to better understand how many people experience long-lasting symptoms in order to prepare for and address potential public health and societal impacts.

Currently, we are well aware of the fact that COVID-19 is a complex disease that can have profound effects on nearly every part of the body during acute infection as well as over the longer term. We know that even if a small proportion of those infected with SARS-CoV-2 globally, go on to experience PASC, the societal impacts could be profound. The importance of preventing the long-term health effects of COVID-19 cannot be overstated. Perhaps, the currently available vaccines may help in mitigating the effects of PASC. This is just one of many reasons why universal access to COVID-19 vaccines should be a global priority. There should be no argument whatsoever about it.