If difficulties occur in developing reliable case definitions, there are serious consequences for patients, as they would then be unsure whether or not they have the illness, as well as for scientists, who would then have difficulties in finding biomarkers.
This has occurred for the post-viral illness known as chronic fatigue syndrome, which most patients refer to as Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). The consequences have been devastating in terms of increasing stigma for these patients with ME/CFS as when biomarkers are not reliably identified, health care workers inaccurately attributed their illness to
psychiatric versus more biological causes.
Will a similar fate occur for the millions of people who have not recovered from the current COVID pandemic?
Patients previously infected with
COVID-19 often have persisting and new symptoms. Many have termed the post-COVID-19 infection phenomenon as “long COVID” or “long haul COVID.” If only 10% develop long haul COVID, then of the 47 million current cases in the US, there will be over 4 million individuals affected. This will have significant consequences on our health care system.
Recently, the internationally respected World Health Organization (WHO) introduced a clinical case definition for those who have not recovered from being infected by COVID. Their criteria suggest that symptoms are usually three months from the onset of infection with a duration of at least two months. Their case definition also mentions that among the common symptoms are fatigue, shortness of breath, and cognitive dysfunction.
A clinical case definition is intended to be very broad so that it can include all those who have the disorder. This is in contrast to a research case definition, which is more restrictive in criteria to identify a more homogeneous sample.
It is unclear why three months have to elapse for a person to have the WHO diagnosis. In other words, those patients who continue having symptoms after the first few weeks of COVID infection are left without a diagnosis for several months, and these first few months might be a critical time for a diagnosis that could help patients secure treatment.
The next part of the WHO case definition is that the symptoms must last for two months. We know that sometimes symptoms are delayed with long haul COVID, so if symptoms emerged three months past infection, a patient would need to be sick again for two months before being provided a diagnosis and possible treatment. It would be simpler to just indicate the amount of time that has elapsed since being infected or becoming sick, as this would eliminate problems associated with individuals not being able to have a diagnose and treatment at the critical early times in the illness.