An enigmatic illness: Long Covid and its implications

From early in the pandemic, many COVID-19 survivors reported experiencing a variety of symptoms many weeks and months after the acute infection phase. In this article, we discuss the multitude of symptoms comprising Long Covid diagnoses and possible associated mortality and morbidity risks. We also discuss potential consequences of repeat infections and the difficulties in comparing reports across different time periods in the pandemic. While Long Covid has so far had a modest impact on insurers, the disease warrants ongoing monitoring to be better understood.

Long Covid, or post-acute residual symptoms of COVID-19, has a range of definitions, varying by country and/or research study. Long Covid encompasses a number of debilitating or partially debilitating physical or psychological symptoms, usually starting 8-12 weeks after the initial COVID-19 infection¹. Long Covid symptoms are typically different from those experienced during the initial infection, and currently there are few objective tests to measure reported symptoms.

Symptoms of the first wave COVID-19 featured a dry cough, high fever and shortness of breath. These evolved with new variants and alongside vaccine and recovery immunity to cause a less severe respiratory condition resembling the flu. The Omicron variant which appeared at the end of 2021 was much more transmissible; but largely caused milder symptoms than previous waves. Long Covid symptoms differ from those of the acute infection. The immediate and noticeable symptoms of COVID-19, the cough and fever, decline while newer symptoms appear, and other residual symptoms persist. Patients with COVID-19 who were hospitalised or under medical care and survived the initial infection appear to be recovering. However, some studies have suggested that 3% of the population subsequently report symptoms that impact their daily lives, such as a shortness of breath, fatigue, and brain fog, while other studies report a drop from 19% to 11% of Long Covid symptoms in the space of 6 months ^2 3. Many of these symptoms are difficult to observe and quantify, rarely causing a need for acute hospitalisation or medical attention.

Long Covid is still an emerging condition with considerable variation in presentation. In trying to define the condition with greater precision, researchers have grouped symptoms by predicted short-term and long-term mechanisms and potential impacts on health - including a possible range of likely severities and durations (Figure 1).⁴ While there is no standardised way of symptom clustering, one approach is by medical specialty, including:

• Neurological symptoms such as fatigue, brain-fog, headache, changes to smell (anosmia/dysosmia) and delirium.
• Psychiatric symptoms: depression, anxiety. ​
• Cardiorespiratory symptoms, including chest pain and severe shortness of breath.
• Systemic/inflammatory symptoms, abdominal symptoms, myalgias, and changes in skin and hair.

In addition to these, it is possible that COVID-19 infections may also induce symptoms or diseases later in life that are secondary from the initial infection, triggered by subsequent organ or tissue injury (Figure 2).⁵ There is some empirical evidence to estimate incidence or risk across a range of diseases, and this remains an important area to monitor.

Medical science is as yet unable to pinpoint an onset of and susceptibility to Long Covid. While the root cause is primarily past COVID infection, recent studies have reported around 30% of Long Covid cases where 3 or more symptoms were reported, are of an unknown cause – perhaps caused by conditions with no links to COVID-19 at all⁶. Patients who developed severe acute COVID-19, as well as those with mild symptoms or even asymptomatic, appear at risk of Long COVID.

The SARS-CoV-2 virus (the virus from which COVID-19 is derived) can persist in the tissue, which is known as a viral reservoir, of some Long Covid sufferers where it can continue to trigger an immune response.⁷ Acute COVID-19 is also known to cause immune dysregulation. This viral reservoir may affect blood clotting, neuroinflammation and neuropathy.

It is likely that individual patients with a Long Covid diagnosis have different underlying biological factors driving their symptoms. The US Centers for Disease Control and Prevention (CDC) considers the following groups more susceptible to Long Covid in the US⁸:

• People who were hospitalised or experienced more severe COVID-19, especially those who needed intensive care.
• People with underlying health conditions prior to COVID-19.
• People without a COVID-19 vaccination.
• People who experience multisystem inflammatory syndrome (MIS) during or after a COVID-19 illness.

The susceptible groups of Long Covid patients may change by country or region, as approaches may vary between healthcare opportunities, patient engagement and care options. 

Available diagnostic tools mainly focus on post-COVID infection respiratory symptoms. However, mounting evidence suggests that Long Covid can result in a range of residual symptoms beyond respiratory issues⁹. Currently, there are no comprehensive tests or universal definitions to diagnose Long Covid, which makes it a subjectively clinically determined condition. Nevertheless, efforts are underway to develop reliable diagnostic tests capturing the full range of Long Covid symptoms, with hope for expansion of treatment options as diagnosis improves¹⁰.

A variety of clinical therapies are offered against Long Covid symptoms, including drug-based interventions for specific symptoms, psychological treatments and respiratory physiotherapy. However, the ongoing impact of COVID-19 on global healthcare resources, including workforce shortages, healthcare backlogs and economic constraints, may limit access to these treatments.

Some Long Covid symptoms dissipate over a short period of time, while others may linger for several years or cause an overall change in health. The true outcomes of Long Covid will only fully be seen in years to come.

Recent studies indicate that people with repeat infections are at higher risk of lung, heart, and brain conditions.^11 12However, many of these studies have several limitations – including the widely cited study on the healthcare database of the US Veterans Health Administration of 500,000 veterans between March 2020 and April 2022. The study is not representative of the wider or insured population with a 90% male cohort, older than average. Additionally, the participants were predominantly unvaccinated until at least halfway through the study; and with varying levels of immunity to different variants. Furthermore, given the limited duration of the study, the potential for likely changes to trajectory and hazard ratios were not captured.¹³ The study found that compared to noninfected controls, the cumulative risk of Long Covid appeared to increase relative to the number of repeat infections, although the exact relationship remains unclear.  Evidence showed that reinfection, following an initial infection with the earliest SARS-CoV-2 variants, further increased the risk of death, hospitalisation and sequelae in multiple organ systems in the acute and post-acute phase.  Another larger cohort study found that all-cause mortality was notably elevated in upper age-groups in the first five weeks following infection, and elevated (to a lesser degree) in the first post-infection year.¹⁴

Further studies will be needed, as presentations of Long Covid are wide ranging and change over time. Symptom duration is uncertain and repeat infection will likely continue to strengthen immunity against subsequent severe infections in healthy individuals, provided that newer variants are milder. This will need to be weighed up against the long-term risk of repeated infections as a trigger for Long Covid. 

Future research studies will also have to be more discerning than current studies and will likely not combine individuals from different variants, vaccination and infection statuses in the same bucket. With social and personal restrictions fully phased out, future protection for the most vulnerable individuals will likely be mostly derived from vaccination. It is expected that there will be a continuous cycle of viral evolution and vaccine development, as pharmaceutical companies look to refine existing formulations against the contemporarily circulating variants, providing ongoing protection.

As COVID-19 becomes endemic, the vast majority of individuals – vaccinated or not – will have contracted the virus, and this would also hold true for the insured population. If the early studies prove true, both Long Covid and health impacts from repeat COVID-19 infections may increase the burden of disease for all populations. This, in turn, could lead to additional healthcare costs for society. Insurance companies could see associated developments in their portfolios. Over time, COVID-19 is likely to become a seasonal condition of repeated waves.

Disability Income

An initial risk for private insurers was an increase in disability income (DI) claims due to mental health and Long Covid-related musculoskeletal conditions and physical impairments. Currently it appears that industry-wide material increases in the level of DI claims have not been reported. This may be attributed to the following factors:

• The increased workplace flexibility during the pandemic allowed many with some level of physical or mental disability to work from home, which may have partially contributed to the lack of increase in private insurance DI claims. Working from home has retreated from levels predicted during the height of the pandemic, so this trend may not continue in the long run.
• Long Covid symptoms may not have been sufficiently debilitating to trigger DI claims or long lasting enough to exceed waiting periods.

However, considering the spectrum and the post-infection time of symptom onset, the risk remains that DI claims may become elevated should more people be diagnosed with Long Covid.

Mortality and Critical Illness

Long Covid, in some forms, has been associated with organ damage and auto-immune responses that may have a tail of morbidity and mortality. This will inevitably take some years to manifest and appear in the data, but is key to monitor as an ongoing research topic. 

Many countries are currently experiencing excess cardiovascular mortality and morbidity. While these may be misreported COVID-19 deaths, findings from recent studies indicate that at least some proportion of this could be due to post COVID complications.¹⁵ L&H insurers should continue to monitor this as they estimate mortality levels in the coming years.

Despite the many uncertainties relating to Long Covid, existing research suggests an elevated risk outlook. Additionally, several government healthcare agencies have reported an increase in excess mortality, which continues to remain high compared to pre-pandemic levels. Both underwriting and the generally healthier portfolio of insured populations should mitigate potential impacts for L&H insurers; however, risks remain.  

Although the worst of the pandemic appears to have passed, our experience and understanding of the long-term impact of COVID-19 continues to evolve. As observation time increases and more studies are conducted, further insights into the impacts of Long Covid on mortality and morbidity will assist in a clearer risk assessment and quantification of impacts. Until such time, practitioners in the insurance space may seek to factor in these considerations and potential impacts in their risk outlook.