The science underpinning policies to deal with COVID-19

Posted on Thursday, March 26, 2020

Author: Prof. Rees Kassen

Rees Kassen

Core Member, ISSP
Professor of Evolutionary Biology, Faculty of Science, uOttawa

‘Don’t panic’ says the cover of The Hitchhiker’s Guide to the Galaxy. Sage advice in any time. Especially now.

To say COVID-19 has changed our lives seems a gross understatement. We are all feeling the impacts of social isolation, whether it is as benign as working from home or as drastic as quarantine, and wondering how long this will last. Anxiety is the new normal. Panic feels just steps away.

A little knowledge can go a long way to dialing down the anxiety meter. Knowing what we are up against and why we are being asked to change how we interact with the world can, I hope, help us get through these anxious times and start planning for the future. So, let’s get started.

The current pandemic is caused by the SARS-2-CoV coronavirus. The disease is called COVID-19. Coronaviruses are a family of RNA viruses infecting many different animal species, including camels, cattle, cats, bats – and humans, where they cause respiratory illnesses like the common cold and more severe diseases like Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). The name 'Coronavirus' refers to the crown-like (Latin: corona) viral envelope that can be seen with electron microscopy. You might also see the virus referred to as SARS-nCoV-2 or just nCoV-2. The 'n' stands for novel, meaning it is novel to humans. More on that below.

Infections are caused by the virus colonizing the respiratory tract, mainly through droplets resulting from coughing or sneezing. The virus is easily transmitted among people, which is the main reason it has emerged as a pandemic. Estimates are that, for every person carrying the virus, about 2.5 additional people they come into contact with will become infected. That’s a high rate of transmission. The comparable number for seasonal influenza is about 1.3, and for the 1918 Spanish flu (to which many are comparing this pandemic) the number was only about 1.8. Case fatality rate (CFR; the number of confirmed infections resulting in death) is still uncertain but seems to be ~1% on average, although it increases dramatically in people over 65 years. For comparison, CFR for seasonal flu is ~0.1% whereas the SARS outbreak in 2002 was about 10%. 

What do these numbers mean? The high transmission rate means the virus spreads rapidly – like wildfire. We are seeing this happen in most countries around the world right now, including Canada. A country reporting small numbers of cases now does not mean the virus isn’t spreading. Rather, it could be that testing for the virus is not being done, cases are going unreported, or the first cases arrived only recently. Never matter. The virus will spread, and it will get worse before it gets better.

A virus that spreads easily infects a lot of people. Even if a small fraction of infected people develop disease severe enough to land them in hospital, so many people will be infected that our health care system could be quickly overwhelmed. A small fraction of a very large number is still a large number, after all. This is why we need to do everything we can now to prevent the disease from spreading. Slowing the rate of spread (#flattenthecurve) gives the medical community a fighting chance to treat the sickest patients one by one, rather than all at once.

Reducing transmission means making sure the virus has as few opportunities to spread as possible. We need to go from a single case infecting 2.5 people to a single case infecting less than 1 person. If we can do that, the virus will stop spreading. There are some pretty simple things we all can do to help: wash your hands (for at least 20 seconds with soap and water) and physically distance yourself from others (at least 2 meters). Governments could impose other measures to reduce the spread. Hard choices will have to be made. This article provides a start for how policymakers could think about those choices.

Looking ahead, we need to find ways to prevent future pandemics from happening. COVID-19 has become a problem because it jumped the species barrier – evidence points to bats as the source. Crossing the species barrier is unusual because a virus that thrives in one animal species won’t possess the machinery allowing it to both establish (i.e., replicate) in a human cell and transmit from person-to-person. Multiple genetic changes, or mutations, are required for this to happen, though we don’t yet know how many or what environmental conditions promote their evolution. And the experiments required to answer this question can be controversial because they provide information that could be used to generate a pandemic strain of virus in a lab (see this paper as an example). But SARS-CoV-2 managed to cross the species barrier, just like SARS-CoV-1 from 2002 and influenza H5N1 in 2009 before it. It can, and will, happen again. We need to do a better job at predicting when and where.

The world has not known, in living memory, a pandemic on the scale of what we are living with COVID-19. Physical distancing, self-isolation, and restrictions on travel are just the most immediate changes to our daily lives. Coming soon we need to prepare for challenging times as the economy tanks, more shops and businesses close, and the cultural fabric of our lives – from sports to the arts – steadily unwinds. The science behind this outbreak is not that mysterious; epidemiologists have excellent models for predicting how the virus will spread, and evolutionary biologists have a good grasp of why viruses sometimes make the jump from animals to humans. The challenge moving forward will be how to put these principles and models together with high quality data and effective policy to ensure that future outbreaks either don’t happen again or, if (more likely when) they do, we are better prepared to manage them.

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