Even if you recover from Covid-19, you may not escape unscathed...
At the moment, official record-keeping offers only three options when it comes to Covid-19: infection, recovery, or death. This misses a broad range of other potential outcomes for people who catch the virus — many of them bad.
In medicine, physicians talk about “M&M,” or “Mortality and Morbidity.” Many hospitals even hold closed-door “M&M” conferences, where their providers discuss everything that’s gone wrong with their patients over the last week or month.
Mortality is a pretty straightforward concept. Have patients died from a particular disease process, and if so, how? Were their deaths avoidable? Can the field of medicine learn anything from them which will improve patient care in the future?
Morbidity, though, is a much trickier concept. It includes the complications, health issues, and other negative outcomes (other than death) that a disease causes. Basically, it’s all the ways that a disease can make you unwell, even if it doesn’t actually kill you.
Official statistics capture deaths that occur from Covid-19 reasonably well. Reporting methods are often updated, and epidemiologists have gone back and attempted to quantify Covid-19 deaths that were originally missed. But overall, death counts are a relatively easy metric to apply. Patients are either alive or dead. Knowing the difference is comparatively simple.
But these official statistics miss quite a lot. Specifically, they fail to represent Covid-19 morbidity — the harm that the disease causes, even in people that it doesn’t kill. In terms of measuring the long-term impact of the disease — and accurately evaluating risk — that’s a big problem.
Mounting evidence shows that even if Covid-19 kills less than 1% of patients, it doesn’t necessarily leave the others it infects unharmed. Even those who have “recovered” may have long-term impacts from it.
Morbidity can happen over a long-term period, so it is a harder variable to study and track in the early stages of a pandemic than death. Anecdotal reports and early data, though, show that Covid-19 morbidity may be a very real concern. According to a report in The Atlantic which followed several people with Covid-19 over multiple months, many had long-lasting symptoms and impairments (including headaches and debilitating fatigue) that didn’t resolve when their active infection stopped.
All of these cases were considered “mild” and didn’t result in the use of a ventilator or a stay in the ICU. And they occurred in people from a variety of age groups, not only older adults and the infirm. Yet despite these “low risk” factors, patients were still experiencing major impacts from the disease months after contracting it.
A handful of studies about Covid-19 (as well as scholarship on previous coronaviruses) bears this out. Covid-19 infection can have long-term impacts on the lungs, heart, immune system, and even the brain. These include an increased risk for heart attacks, future respiratory infections (including more severe cases of flu), and neurological impacts like cognitive impairment.
These are in addition to the known risks for hospitalization, especially if a hospitalization results in an ICU stay and might trigger ICU delirium, a condition that can be permanent. Just because you’ve recovered from Covid-19 doesn’t mean you’ve necessarily escaped unscathed — especially if the disease landed you in the hospital.
Even more concerning is emerging data showing that “asymptomatic” Covid-19 infections can cause long-term damage. Recent studies, including one published in Nature Medicine, have found “ground-glass opacities” in the lungs of asymptomatic carriers of Covid-19 — evidence of inflammation which could be causing damage internally, even if the patient feels completely fine.
And although earlier evidence suggested that children are less affected by the disease, the emergence of a new condition, Multisystem Inflammatory Syndrome, suggests that the virus may be having longer-term impacts even on the young. MSIS symptoms can emerge weeks or months after the original infection and can be deadly without prompt treatment.
All these early reports point to the possibility that Covid-19 causes acute infection, but also long-term inflammatory damage. Inflammatory diseases are the leading cause of death worldwide. If Covid-19 worsens these conditions — or causes its own long-term inflammatory damage — the result could be millions of additional deaths from heart disease, diabetes, asthma, and the like, especially in already vulnerable populations. These effects of the disease may not be apparent for years or decades.
At the moment, official statistics largely fail to take such ongoing health impacts of the coronavirus into account. Traditional epidemiology does have metrics for morbidity. But they tend to focus on disease prevalence. Once a person’s active infection has passed, they are often no longer followed or counted.
As risk professionals like Nassim Nicholas Taleb have pointed out, the failure to measure Covid-19 morbidity makes it far harder to evaluate the true risk from the pandemic. Simply looking at deaths is not enough. Mortality statistics fail to account for the people who survive the disease but suffer long-term harm — or those who die from its complications long after their initial infection has subsided.
This blindness to morbidity may push populations toward more aggressive reopening, or away from risk-reduction measures like mandating face coverings. If deaths are declining, the picture may appear rosy. But in reality, the disease may be causing irreparable harm to millions of people — just in a way that’s invisible in current statistics.
In an increasingly polarized world, morbidity is an issue that cuts across political lines. Even if your primary goal is to restart the American economy, you should care about Covid-19 morbidity. Chronically sick people often have a hard time working, or the efficiency of their work suffers. Several of the patients profiled in The Atlantic experienced “brain fog” and other neurological effects from the virus, and have found even simple activities like housework and yoga challenging. These patients would almost certainly have a hard time returning to work. To achieve lasting economic recovery with minimal burden from worker illness, Covid-19 morbidity has to be accounted for.
Thankfully, tracking Covid-19 morbidity doesn’t require reinventing the wheel. Medicine and risk management already have a robust tool for measuring the impact (health-wise and financial) of morbidity: the Quality-Adjusted Life Year (QALY) and its sister statistic, the Disability-Adjusted Life Year (DALY).
QALYs and DALYs take into account both a person’s life expectancy and their quality of life (defined, broadly, by how much a disease affects their ability to perform daily tasks). Lowered life expectancy affects QALYs, but so do long-term disease effects like the kind we’re beginning to see from Covid-19.
QALYs and DALYs are often used to evaluate new treatments. But there’s no reason QALYs and DALYs couldn’t be applied more broadly, to estimate and measure the disease burden of the Covid-19 pandemic on a given population.
In the early stage of the Covid-19 pandemic, QALYs and DALYs could be applied by deciding on an estimate for a “weight factor” measuring the severity of Covid-19’s impact on patients’ health (this is usually done on a scale of 0 for “perfectly healthy” and 1 for “dead”). This weight factor could be set differently for different populations. For example, older people with Covid-19 or those with more preexisting conditions could receive a higher weight factor.
Using demographic data for a particular population (mean age, prevalence of existing diseases, etc.) and these weight factors, an estimate of the impact of Covid-19 morbidity could be established for a population. This could then be multiplied by the number of confirmed infections in the population to arrive at a crude estimate of the overall burden of Covid-19 morbidity.
Accounting for morbidity in this way could have some major impacts on plans for reopening. Regions with highly vulnerable populations (those expected to suffer more morbidity as a result of Covid-19 infections) could reopen more slowly. And those with relatively lower projected morbidity might be emboldened to open more quickly.
As the pandemic continues and more data on the long-term impact of Covid-19 becomes available, weights could be adjusted. If it emerges that certain populations are less vulnerable than expected, their weights could be adjusted downward. If more long-term impacts of Covid-19 infection emerge (like breathing issues in asymptomatic carriers), weight factors could be adjusted upward.
QALYs and DALYs are not perfect metrics. Setting weight factors is inherently subjective, and can reflect biases present in a society. At the early stage of a pandemic, very little data is available, so estimating morbidity is more an art than a science. There are also ethical concerns with QALYs and DALYs since they’re often used to weigh the value of one life against another. QALYs and DALYs can also miss the hard-to-measure impacts of disease, like their impact on mental health.
But given that Covid-19 morbidity is basically invisible in current public health models, measuring morbidity with metrics like QALYs and DALYs would at least be a helpful start. It could begin to give us a way to estimate not only how many people will die from Covid-19, but how many lives will be negatively impacted by the disease.
Measuring morbidity could also provide better treatment and follow-up. Current approaches assume that once an asymptomatic carrier of Covid-19 tests negative, their disease has run its course. Follow-up for these patients is likely to be limited. If it turns out that Covid-19 causes ongoing morbidity in patients who appear healthy, providers could shift toward monitoring them months or years after their infection (looking for evidence of inflammation and lung damage, for example).
On a personal level, if you’ve tested positive for Covid-19 and feel fine now, don’t assume your disease is over. Especially in the longer term, be aware of potential Covid-19 symptoms, and talk with your doctor about testing for any long-term impacts that emerge.
And if you still have symptoms after your Covid-19 test has turned negative, and are told that these are unrelated to the disease, be skeptical. In the grand scheme, very little is known about Covid-19. You may be experiencing lingering effects from your infection, which your doctor should help you address and manage.
Tracking deaths and recoveries is a start. But current approaches to tracking Covid-19 are binary — you’re either positive or negative, alive or dead. To truly measure (and react to) the long-term impacts of the pandemic, we need more nuanced measures.
Specifically, we need a way to measure morbidity. Otherwise, we risk missing impacts of Covid-19 which could have massive, invisible consequences — especially for our most vulnerable.