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Understanding the impact of Long COVID has presented any number of difficulties, not only to the medical fraternity but also to insurers. There have been widely varying reports of the prevalence; from 10 to 90%.1 One pundit estimated between 4.5 and 27 million Americans will experience the effects of Long COVID.2
A clear definition of the condition has helped,3 but the lack of data from representative samples followed over time, rather than from cross-sections of self-selected populations, has left a confused picture. Studies largely failed to control for complaints that were present prior to the infection. Many of the early reports of the long term physical and mental health effects of COVID-19 were criticised for their poor quality4 and it is only now that a clearer picture is beginning to emerge.
The UK Office of National Statistics (ONS) recently reported that the likelihood of reporting Long COVID, 12 weeks after infection with the BA.1 or BA.2 variants of Omicron, was 4% in those who had been triple vaccinated. Although there were superficial differences between the variants, once adjusted for a number of characteristics “there was no statistical evidence that the likelihood of self-reported Long COVID differed between the Omicron BA.1, Omicron BA.2 and Delta variants among triple-vaccinated adults”. In terms of significant impairment of activity, the variants did not differ in this highly protected population.
By contrast there were bigger differences in reporting Long COVID problems between the Omicron BA.1 and Delta variants (4% vs 9.2%) for the population who had received only two vaccine doses. There was also a greater functional impairment in the Delta variant compared with the other variants (5.5% vs 2.7%).5
As the number of people experiencing COVID-19 infections rose during early summer in the UK, concern was raised about the number of people who would require intervention for the sequelae of acute infection, but the levels of persistent functional impairment reported are not as high as might have been feared.
Others have been keen to stress that their samples are large, representative and account for pre-existing symptoms.6,7 Forty percent of a U.S. cohort reported at least one persisting symptom 12 weeks after reporting a COVID-19 infection. This was reduced to 23% once pre-existing conditions were excluded.
The percentage reporting fatigue during the 12 weeks post-infection dropped from 21% pre-infection to 18% (although this was not statistically significant).
Dry skin, sneezing, abdominal discomfort, chest congestion, shortness of breath and sore throat were more common. For those who had symptoms that lasted throughout the 12 weeks, so-called “long haulers”, fatigue was common (50%). However, 45% of those reporting fatigue also experienced the problem prior to COVID infection.
The most frequently experienced new-onset persistent symptoms among the long haulers included headache (22%), runny or stuffy nose (19%), abdominal discomfort (18%), fatigue (17%), and diarrhoea (13%). The investigators noted that vaccination was not widely available in the U.S. at the time the data was collected, and they speculated that widespread uptake and the different variants may influence the long-term outcomes.
In the Netherlands, approximately one in eight had persistent problems that included chest pain, problems breathing, painful muscles, anosmia and general tiredness after controlling for pre-existing difficulties. Twenty-three somatic symptoms were investigated in a group who had been infected by COVID-19 and a control group who had not. The population was not ethnically diverse. In a commentary on these results the value of identifying core symptoms of Long COVID was stressed. Prior to these studies this was problematic, as a wide variety of persistent complaints were linked to the infection.8
The importance of identifying core symptoms is reinforced by the identification of distinct Long COVID symptom profiles associated with different variants of the virus.9
The greatest impact on daily living was found when a combination of systemic, respiratory and neurological symptoms was reported. The authors concluded that these data demonstrated that Long COVID is not a single entity but appeared to have several clear subtypes.10 This should not come as a surprise as Long COVID is a heterogenous condition with a variety of potential underlying mechanisms that are yet to be fully understood, but include acute organ damage and long-lasting inflammatory changes.11
So far, few studies have produced clear evidence concerning the question of vaccination status and persistence of symptoms. There is, however, a growing body of literature that supports the idea that full vaccination leads to a substantial reduction in, but not elimination of, the risk of developing Long COVID. Clinical practice suggests that many of those who are vaccinated while experiencing Long COVID find that their symptoms improve.12,13
These recent, methodologically sound, studies are important to insurers. They are building a clearer picture of the prevalence of Long COVID, which is proving to be at the lower end of previous estimates. They contribute to a better understanding of the core features and the impact of virus strain and vaccination status on long-term outcomes. With this comes the potential to better understand the underlying mechanisms and the possibility of personalised treatments based on the symptom profile and biomarkers.
An understanding is developing that, as with so many other illnesses, a diagnosis is not the same as a disability, but the presence of certain symptom clusters increases the risk of long-term problems without early intervention. This data helps to manage expectations of recovery and to ensure that the person has a management plan that is best tailored to their needs.
The effects of the COVID-19 pandemic are far from over but they provide an important opportunity to examine practice and ensure development is based on robust, quality evidence as a blueprint for the future.
I am grateful to Dr. John O’Brien, Gen Re’s Chief Medical Advisor, for his comments on earlier drafts.
