SPOILER ALERT: The devastating storyline of COVID-19 will not end with a Hollywood-style victory. In the next chapter, we can expect COVID-19's unfortunate legacy to sadly extend beyond the defining biometric implications, including acute respiratory deaths, we experienced during the peaks and troughs of its pandemic phase. It will be defined by a frustratingly persistent endemic ‘normality' with enduring impacts on the mortality and morbidity of the UK population who lived through it all.
Whilst we can confidently predict this broad transition will take place, pertinent questions remain about the scale of future impacts. The pandemic will affect the health of the population in many ways. Some of its more indirect influences will take years to become evident, but here we focus on some of the direct longer-term effects for those who survived a prior infection. Can we say anything about the future mortality and morbidity of these people?
Persistent symptoms
Since early 2020, over half a million people have survived a COVID-19 hospitalisation in the UK, and this is only a fraction of the numbers who have suffered moderate symptoms in their own homes. However, although hospitalised patients tended to fare proportionally worse than the latter cohort, the impact on those who managed their symptoms at home remains significant.
It is increasingly well-known that many whose initial infection was relatively mild develop long-term impairments. ONS data suggests 1.7 million people self-reported ‘Long COVID' in March 2022. In contrast to the hospitalised patients, who often reported respiratory symptoms associated with lung damage, those never hospitalised more often report fatigue, chronic pain and ‘brain fog'. Many are slowly moving towards a full recovery, but a substantial proportion appear to have developed intractable symptoms; 45% (i.e. 765,000) reported having symptoms for at least one year.
Pressures on the workforce
In a study of 2230 participants who had been in hospital with COVID-19, only 25% felt fully recovered five months later. At a one-year follow-up of those same participants, the number reporting full recovery rose only slightly to 29%, with half of those still impacted having symptoms described as ‘severe' or ‘very severe'. The study indicates that we may be past a tipping point whereby COVID-19 would have significant and enduring impacts on the workforce.
An eye on mortality: Comparisons to pneumonia
Unfortunately, the advent of the endemic phase of COVID-19, will not mean the end of mortality relating to the virus. In additional to lower-level acute mortality from future waves of disease, we can expect increased mortality among survivors, especially among those who were hospitalised with COVID-19. A UK government report in 2021, Short Report on Long COVID, identified a strong correlation between cases of COVID-19 hospitalisation and the likelihood of serious adverse events in the months following discharge from hospital.
For instance, the chart below from the study (x-axis represents the risk of developing a condition after a COVID-19 infection compared to the general population (blue) or who have had pneumonia (orange)) indicated that those who survived hospitalisation are five times more likely to have a stroke and 5.5x more likely to suffer heart failure, than those with no recent history of COVID-19. The excess risk of development for those same conditions however, were c.5% and 20% less likely to have the respective diagnoses than people who had pneumonia, indicating how common the diagnoses are after a bout of pneumonia.
Figure 3 demonstrates that cardiometabolic and pulmonary adverse outcomes are markedly raised following hospitalisation of COVID-19 compared to the general population. However, the excess risks were comparable to those seen following hospitalisation with pneumonia.
Extending this analysis further, the authors of the study observed the patterns of these events look very similar to those experienced by patients with pneumonia. The risk is consistently close to 1.0 (i.e. the same) on the chart. It is worth noting, the majority of patients in hospital with COVID-19 do have pneumonia, so this similarity is not unexpected. COVID-19 may be exceptional for its novelty, but aspects of its presentation are similar to existing viruses.
The comparison with pneumonia potentially allows us to look further ahead. Although we can only study COVID-19 patients for up to two years so far, longer-term follow-ups for patients with pneumonia suggest materially higher rates of mortality among all age groups for at least ten years after recovery. We do not know that COVID-19 will behave in this way, but we should prepare ourselves for the possibility of long-term impacts on mortality among previously hospitalised survivors.
What about our immunity?
Future COVID-19 infections will continue to add to the burdens we have experienced over the last two years. Drawing on insights from other endemic infections, on average we might realistically expect the general population to suffer from a COVID-19 infection every two or three years. The apparent severity of each infection will tend to reduce, however. This is not because the virus inevitably trends towards mildness (it does not), but because the depth and breadth of immunity in the community is expected to grow via layering of prior infections and vaccinations. We equally should highlight that waning immunity means these improvements will not be indefinite.
However, even with current high immunity levels, the mortality risk per infection remains broadly similar to influenza, and we must remember influenza is itself a serious disease. As for future Long COVID, early evidence suggests vaccines may roughly halve the likelihood of long-term symptoms, but this would still mean material numbers of new sufferers each year.
The Sequel
The realities of ‘living with COVID' are beginning to emerge. The worst of the pandemic is almost certainly behind us, but those seeking closure - an ‘ending' - may be disappointed. COVID-19 joins the panoply of circulating respiratory viruses in our community. Much in life will return to ‘normal', but some changes will remain. Individual preferences will vary based on our personal understanding and tolerance of risk.
The pandemic - the immediate emergency - ends not with jubilation as the credits roll, but slowly, almost imperceptibly, as we come to terms with its effects. COVID-19, on the other hand, does not end.
One day, the World Health Organisation will declare an end to the ‘Public Health Emergency of International Concern', but the moment will be anti-climactic. It will be a mere symbolic interlude as we prepare for the virus to remain with us.
