How Deadly Is COVID-19?

How Deadly Is COVID-19?

With over 90,000 cases of the novel coronavirus confirmed worldwide and over 3,000 reported deaths, scientists are zeroing in on how deadly the virus is and who is most at risk. The latest research suggests the fatality rate is anywhere between 1.4 and 2.3 per cent, but the true impact of the virus is actually more complicated—and likely less severe—than that.

The ongoing COVID-19 outbreak is still in its early stages, having emerged in China at some point in late 2019 and spread to dozens of countries in early 2020. There’s plenty we don’t know about this virus, called SARS-CoV-2, but a clearer picture is starting to emerge in regards to how it spreads and who’s most at risk of both contracting and dying from this disease.

Before we get into the latest research, however, it’s important to understand how a SARS-CoV-2 infection actually leads to death.

This new coronavirus is similar to SARS, which stands for “severe acute respiratory syndrome,” which is why the virus itself is informally referred to as SARS-2. The disease, which is associated with fever and cough, has also been referred to as NCIP, which stands for “novel coronavirus (2019-nCoV)-infected pneumonia.” As both of these titles suggest, the disease affects the lungs and our ability to breathe. In severe cases, the arising pneumonia can trigger a dangerous condition known as acute respiratory distress syndrome (ARDS), which causes the lungs to fill with fluid and become rigid. This makes breathing difficult, if not impossible, requiring some patients to be hooked up to mechanical ventilators. Consequently, death from COVID-19 is typically due to massive damage to the lungs and progressive respiratory failure, according to recent research published in the Lancet.

So that’s how COVID-19 kills, but how deadly is it overall?

A study published in the New England Journal of Medicine (NEJM) on February 28, 2020 presented an overall fatality rate of 1.4 per cent. These figures, compiled by the China Medical Treatment Group for COVID-19 and many other Chinese institutions, were based on 1,099 patients who were admitted to 552 hospitals across China up until January 29, 2020. The median age of these patients was 47 years, of which most—58.1 per cent—were male. Of the 5 per cent of patients who were admitted to intensive care units, 2.3 per cent had to undergo invasive mechanical ventilation, which, more often than not, failed to save their life.

In a related article published in the New England Journal of Medicine, Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, along with his co-authors, wrote that the COVID-19 outbreak poses “critical challenges for the public health, research, and medical communities,” but that the actual death rate from the disease is likely lower than the rate reported by the Chinese researchers. The reason, they say, is that many cases are mild and thus are not being reported.

“If one assumes that the number of asymptomatic or minimally symptomatic cases is several times as high as the number of reported cases, the case fatality rate may be considerably less than 1%,” wrote Fauci and his colleagues in the letter.

Assuming this is correct, that means the health consequences of COVID-19 are more akin to severe seasonal influenza, which is associated with a 0.1 per cent death rate, or the pandemic influenza outbreaks of 1957 and 1968, according to Fauci et al. These figures are mercifully much lower than the fatality rates of two other notorious coronaviruses, namely SARS (death rate between 9 and 10 per cent) and MERS (death rate of 36 per cent), according to research published in Nature Reviews Microbiology in 2016.

These are all preliminary estimates, and much still needs to be learned about SARS-CoV-2 and how it works. Recent figures put out by China’s Centre for Disease Control in Beijing presented a fatality rate for COVID-19 at 2.3 per cent. This is probably way too high, for the reasons previously mentioned, but it’s alarming nonetheless. This rate was based on 44,672 cases reported as of February 11, 2020.

Now, to claim that people have X-per cent chance of dying from a disease is a rather blunt and not entirely informative statement, as this rate applies to the total infected population. Statistics from China CDC are providing a more nuanced look at the disease and who’s most at risk.

Men appear to be more at risk of both contracting and dying from COVID-19; China CDC stats show that 2.8 per cent of males have died from the disease, compared to 1.7 per cent of females. It’s not immediately clear why this should be the case, but many sociological and cultural factors could explain why men might be more prone to contracting the disease (e.g. perhaps more men in China travel for work).

That said, the most significant risk factor for dying from COVID-19 is age. According to China CDC, people above the age of 80 have a 14.8 per cent chance of dying from the disease; people in their 70s, 8 per cent; people in their 60s, 3.6 per cent; and people in their 50s, 1.3 per cent. Once below this age range, the risk of dying drops to between 0.2 and 0.4 per cent. Again, these figures could be inflated due to the fact that a plethora of mild cases likely aren’t reported.

In addition to age, pre-existing medical conditions are also a major contributor to death from the disease. COVID-19 patients who also had cardiovascular disease had a 10.5 per cent chance of death; diabetes, 7.3 per cent; chronic respiratory disease, 6.3 per cent; hypertension, 6 per cent; and any form of cancer, 5.6 per cent, according to China CDC stats. Clearly, advanced age plus any of these conditions are a dangerous combination.

Other research published in the NEJM last week describes the “early transmission dynamics” of the disease. This study, co-authored by Qun Li from the China CDC, looked at the first 425 cases reported in Wuhan, China, the epicentre of the epidemic. This research included cases from December to January 22, 2020. The figures provided in this paper are important, but again, they need to be treated with caution given that this data was collected during the earliest stages of the outbreak.

At a median age of 59 years, the patients were a bit older than those reported elsewhere. Of these patients, 56 per cent were male. There were no reports of children under the age of 15 with the disease. The reason is that “children might be less likely to become infected or, if infected, may show milder symptoms, and either of these situations would account for underrepresentation in the confirmed case count,” according to the authors. If this is indeed the case, that means scientists don’t possess a full picture of the current outbreak, at least according to this limited sample.

The incubation period of the disease is around five days but can be as long as 12 days in some cases, according to the Li study. Importantly, this evidence supports the 14-day quarantine period for exposed individuals.

Patients who had to be admitted to hospital tended to be between 9 and 12 days into their illness. This delayed onset of serious symptoms could provide important clues about the virus and how it works, as well as “provide a unique window of opportunity for intervention,” Fauci and his colleagues wrote in their related article.

Fauci and his colleagues said that we “should be prepared” for COVID-19 to “gain a foothold throughout the world, including in the United States.” Regrettably, they say we may have no choice but to shift out of containment mode and adopt mitigation strategies instead. These strategies could involve “social distancing,” as worded by Fauci et al, which would involve the isolation of sick people (e.g. staying home), closing schools, cancelling events like seminars and conferences, and working from home, among other measures.

Depending on where you or your loved ones stand on the demographic spectrum, the figures presented in research papers so far are either alarming or a somewhat reassuring. At the same time, we probably shouldn’t compare COVID-19 to other outbreaks, such as influenza. This disease and the ensuing outbreak is its own unique beast. It’s clear from the data that we’re now firmly entrenched in uncharted territory.