Here's an insight into what it takes to become a pandemic, and what will define whether the 2019-nCov outbreak is at risk of becoming the next global health disaster.
With over 28,344 cases and 565 deaths, scientists are in a race to find a cure for the deadly coronavirus that has sparked global fear and concern.
The outbreak was classified as a global public health emergency by the World Health Organization (WHO) on January 30, provoking fears that the outbreak could be a pandemic similar to the 2009 flu, with estimated mortality rates ranging between 100,000 to 400,000 people.
What's a pandemic, anyway?
According to the WHO, a pandemic is defined as the “worldwide spread of a new disease”. While epidemics are specific to one region, pandemics are global with more cases and higher rates of death. Notable historical examples include the Flu Pandemic of 1918, and the Black Death. A pandemic only describes how widespread a disease is however, and says nothing of its severity.
But with the virus cropping up worldwide, experts believe that it’s only a matter of time before we start calling it a pandemic.
“[It’s] very, very transmissible, and it almost certainly is going to be a pandemic,” said Anthony Fauci, Director of the US National Institute of Allergy and Infectious Diseases, in an interview with the New York Times.
But just how far could the current outbreak of 2019-nCov reach?
The answer to that is found in two key questions. First, how easily does it spread? Second, how deadly is the virus?
While scientists are sparing no effort in researching the virus and trying to find a cure, most research conducted so far is preliminary and likely to reach solid conclusions in the months to come.
At the heart of it all is a little known number that describes the lethality of any given virus.
The R0 explained
With every outbreak of disease, epidemiologists calculate how far and fast a virus is likely to spread. They measure this using the basic reproduction number, called the “R naught,” or R0.
The number describes how many people one infected case is likely to infect on average in a group that’s at risk of the disease.
The R0 can be a big indicator of just how large an outbreak the disease will be. The higher it is, the greater the risk of high infections.
For instance, one of the most contagious viruses known is measles, which can remain in the air of a room for up to two hours after an infected person coughs or sneezes. Without vaccinations, measles’ R0 can reach as high as 18.
Ebola is much deadlier, but less efficient. With an R0 of just two, it is still dangerously lethal but most infected cases die before they can contaminate others.
Here’s the kicker, though: the R0 of a disease can change. The R0 is subject to the environment as well. For instance, some individuals are more contagious, called super-spreaders. Alternatively, airflow in a hospital can increase infections unnecessarily throwing the R0 off.
The SARS virus had an R0 of two to four. Unfortunately, any virus with an R0 more than one can keep spreading if nothing is done to contain or treat it. Even in cases where a non-lethal virus goes global but remains untreated, it can quickly become endemic. Similar to the common flu, this could mean deaths every year as the virus circulates.
What’s the R0 for 2019-nCov?
Medical researchers aren’t quite in agreement on the R0 yet of coronavirus yet. Maimuna Majumder, a computational epidemiologist at Boston Children’s Hospital and Harvard Medical School estimates an R0 between 2.0 and 3.1. Jonathan Read from Lancaster University found an average R0 of 3.11. Meanwhile, researchers from the University of Bern calculate that it is around 2.2.
The WHO reports more figures, estimating an R0 between 1.4 to 2.5. One Chinese team calculates the R0 at between 3.3 to 5.5.
But these numbers need context.
The US alone has seen nearly 100,000 cases of influenza, which causes the flu, since it began in September 2019, leading to the deaths of 54 children. The SARS outbreak in November 2002, which continued for some months, caused nearly 8,000 infections and 775 deaths in more than 24 countries. MERS was found in the Arabian Gulf in 2012, with nearly 2,500 infections over the last eight years and 850 deaths across over 25 countries.
Coronavirus has spread faster than expected. Hong Kong researchers estimate that the real number of infections could be higher than 40,000 in Wuhan, ground-zero of the outbreak.
This has prompted suggestions that the numbers aren’t accurate, given its rapid spread; prompting concerns that Chinese authorities are concealing the true extent of the outbreak. Others believe that the dead are being undercounted, or that undiagnosed cases exist with less than lethal symptoms that are so mild even the infected person doesn’t realise they’re a victim.
To date however, no cases of transmission without symptoms have been reported. If the case were otherwise, it could pose a significant risk given that the virus takes 14 days to incubate. If the virus was able to infect others for 14 days before showing clear signs of infection, containing its spread would be much more difficult.
Taking all this with a grain of salt however, the R0 is only a measure of the disease’s potential and can be fought with simple steps ranging from washing hands and face masks to active screening and quarantines. Even if the virus has a high R0, these measures could reduce the actual transmission rate.
Is the threat understated?
The 2019-nCov still poses a significant risk to public health, at least for the reason that China’s connection to the outside world has expanded significantly in recent years. In 2005, two years following the first SARS viral outbreak, China only had 233 international air routes connecting it to the world. In 2016 alone, they had tripled to 739, with international travellers going to and from China jumping from three million to over 51 million.
Critically, researchers are still trying to understand the virus; leading to the potential for fake news amid conflicting reports on whether the virus can survive outside a host for any period of time, and conspiracies of cover-ups that could cause more panic than good.
But in regions like Africa, the virus may pose a deadlier risk due to limited infrastructure to test for and treat the virus, or even manage a widespread outbreak. To date, only a few cases have been identified in Africa, prompting concerns that the actual numbers could be underreported or altogether hidden.
Another risk is whether the virus mutates into a more lethal, rapid-spreading form, essentially pushing back medical efforts to find a cure. While some mutated iterations of the virus have already been found, it’s not clear whether they are more dangerous or at risk of becoming widespread.
The speed and danger with which a virus mutates is described as virulence.
According to biologist Michael Farzan, the 2019-nCov consists of a single strand of RNA. Microbes with this form of genome mutate “notoriously quickly” he says. In 2005, Farzan was part of the team that discovered the mechanism by which SARS penetrates human cells.
It all comes down to evolutionary biology. If the virus is transmitting well, it doesn’t need to evolve. If one version of the virus is already widespread, it doesn’t need to adjust to survive. If the virus does become endemic, or seasonal; it’s more likely to evolve to be less dangerous as viruses that kill their host before they transmit are slowly eliminated from the gene pool.