Guest article: Lucas C. Adam & Christiana Franke

From mild to severe symptoms – why we need personalised medicine to treat post-acute infection syndromes (PAISs) 

When the SARS-COV-2 coronavirus cast the world into a pandemic, attention was initially focused on the acute illness and on preventing severe cases. It has now become clear, however, that another challenge will affect our health systems, our economy and our society for a long time to come: Long COVID, also known as post COVID-19 condition. 

It is defined as the continuation or development of new symptoms, which persist over a period of several weeks or months following the initial infection. These symptoms can be mild or severe and may affect both physical and mental functions. The condition has a severe impact on the everyday life of those affected, and it poses significant challenges to our healthcare system. 

One central issue is the fact that the post COVID-19 condition does not present a uniform clinical picture. The symptoms can vary greatly with regard to their type, prevalence and intensity. Some patients primarily experience chronic fatigue, others report cognitive dysfunction, shortness of breath, tachycardia or persistent pains. While most patients can still cope with daily life without needing assistance, others are unable to work or even bed-ridden. 

Interestingly, the post COVID-19 condition is not a completely unique phenomenon. Persistent symptoms can occur after other infectious diseases, too. The medical term for such conditions is post-acute infection syndrome (PAIS). Examples of PAISs include the chronic fatigue syndrome following an infection with the Epstein-Barr virus or prolonged symptoms after dengue or influenza infections. Those syndromes resemble the post COVID-19 condition in many ways: Symptoms are often diverse, difficult to pin down and they lead to high uncertainty regarding diagnosis and treatment. Our experience with PAISs thus far clearly shows how urgently we need structured care-delivery models and intensive research – not only in the area of post COVID-19, but for a broad spectrum of hitherto little understood post-infection syndromes. 

Options for diagnosing PAISs 

There is currently no specific laboratory test or imaging method to reliably detect PAISs. The diagnosis is primarily established through thorough history-taking with a focus on the patient’s symptoms and by ruling out other illnesses. This is particularly challenging, since many PAIS-associated symptoms can also emerge in the context of other conditions. In many cases, the primary infection goes unnoticed or can subsequently no longer be reliably identified. That is why many patients have to undertake an oftentimes wearying odyssey of doctors’ visits, examinations and a plethora of different treatment approaches – often without getting clear answers. 

Moreover, there is no standardised treatment for the condition. Some patients may benefit from moderate physical exercise, while for others, this approach may even aggravate the symptoms. Treatment strategies must be tailored to the individual’s needs – which is a huge challenge for patients and treatment providers alike. 

However, medical differences between individual patients are not the only factor impeding the delivery of targeted care. The personal and social circumstances of those affected also play an essential role. Are they still able to work? Do they have financial security? Do they have a supportive social environment? Or do they have to care for children or family members themselves? These factors influence both the strain caused by the condition and the options for diagnosis and treatment. 

The discourse on optimal care delivery 

A key aspect of the discourse around optimal care is the question of where and by whom treatment should be performed. For milder cases, the first point of contact are the family doctors. They usually know the medical history of their patients and can refer them to the appropriate specialists. But particularly when confronted with more complex cases, general practitioners may reach the limits of their capabilities: A high workload, a lack of guidelines and limited diagnostic options hamper care delivery. For many patients, this can be a source of frustration. 

At the other end of the spectrum, there are patients with severe symptoms, who are unable to access outpatient care. However, a sensible and patient-oriented solution must of course be found for this patient group, as well. In hospitals, a comprehensive set of apparatus-based (medical examination using technical equipment) and invasive (physical interventions on the body) diagnostic tools and methods is available. In addition, this setting allows multidisciplinary teams made up of specialists from different medical areas, such as cardiology, pneumonology, neurology, psychosomatics or physiotherapy, to work together. For severely affected patients, inpatient rehabilitation may be a vital step towards recovering their capabilities. However, inpatient stays are associated with high costs and treatment capacities are often limited. Moreover, hospital environments may cause additional stress for some patients, which, under certain circumstances, could aggravate their symptoms further. 

For patients who are severely impaired but do not necessarily require inpatient care, medical house calls could be a valuable alternative. This way, long journeys can be avoided while at the same time, physicians gain insights into their patient’s home environment, which may help them assess the patient’s stress factors. In addition, house calls often strengthen the trust between patient and treatment provider. This approach has its own challenges, however. House calls are time-consuming, many doctors’ surgeries barely possess the necessary resources to organise them and not all diagnostic options are available in a private home environment. 

To close the care gaps, hybrid care-delivery models are increasingly being discussed. These include mobile medical teams with portable devices for basic diagnostic procedures, digital appointments where specialists can also be included virtually or close collaboration between GP surgeries and specialised PAIS outpatient clinics. The aim of those models is to ensure personalised and needs-based care that takes into account the severity of symptoms as well as the personal circumstances of those affected. 

Hopes and challenges 

In addition to their health-related impacts, PAISs may also entail considerable economic and social consequences. Many patients are no longer able to exercise their profession, which leads to a loss of income and social isolation. Family members often have to take on additional care duties, which imposes substantial emotional and financial burdens on them. This particularly affects highly vulnerable groups, such as people with low income or insecure jobs. 

Despite all challenges, however, there is still reason to hope. Research on PAISs is advancing around the globe. Scientists are working hard to improve their understanding of the biopsychosocial mechanisms of the condition, identify markers for a reliable diagnosis and develop effective interdisciplinary treatment approaches. Public awareness is also growing and, in many countries, PAISs are now recognised as an important health policy task. 

PAISs are a complex health issue with physical, mental and social dimensions. Their treatment does not just require medical expertise, but also a high level of empathy, flexibility and the willingness to establish new care-delivery structures. It will be vital to both meet the needs of patients with mild symptoms and at the same time provide the necessary support to those who are severely affected and heavily restricted in their day-to-day lives.