Testing for COVID-19

By Yolanda Ridge

It’s hard to write about the science of COVID-19 right now because our understanding of the virus is still evolving. But it’s also hard to think about anything else.

One thing everyone wants to know is how and when this pandemic will end. In the best-case scenario, a vaccine becomes available and life goes on as normal. The problem is that it will take at least a year – even with international cooperation, dedication and determination – to develop, test, and then distribute the vaccine worldwide.

To find out more about viruses and vaccines, click on this link to read Virus VS Bacteria – Know Your Enemy on Sci/Why, written by our own Adrienne Montgomerie.

In the meantime, everyone will have to stay at home unless we can find a way to quickly and accurately identity who has the virus and who doesn’t. Unfortunately, testing for COVID-19 has been difficult.

There are two main steps to testing a person to see if they’ve been infected with COVID-19.

Step One: Collect the Sample

The sample must be collected by someone wearing a mask that can protect them from getting infected. It’s done with a nasopharyngeal swab, which is basically a long cotton swab that goes into the nose. 

Photo by cottonbro from Pexels

Unfortunately, both face masks and swabs have been in short supply due to huge demand and manufacturing disruptions. One of the largest makers of nasopharyngeal swabs is in Lombardy, Italy where a lot of people are affected with COVID-19.

Step Two: Test the Sample

Getting enough lab space to do the testing has been difficult as well, since the lab has to be specially designed so the virus won’t spread. The test itself requires specific chemicals and machines, which have also been in short supply.

To find out whether there’s any COVID-19 virus in the sample, scientists look for its RNA. Like DNA in humans, RNA is a set of instructions that makes each type of virus unique. To cause an infection, the COVID-19 virus injects this genetic material into a human cell (it really likes lung cells) along with instructions on how to make copies of it. This allows the RNA to be copied over and over again until the cell dies. Then all those copies of RNA are released in the form of new COVID-19 viruses that can attack other cells.

To find out more, click on this link to watch The Coronavirus Explained & What You Should Do on Kurzgesagt – In a Nutshell.

If someone has the COVID-19 virus, there will be pieces of its RNA in the sample collected during step one. The most common way to test a sample for viral RNA is by something called polymerase chain reaction (PCR). It sounds complicated but PCR is really just way of making more RNA using the virus’s genetic material as a template – not that different to what the virus does itself when it causes an infection. If the virus is in the sample, PCR will produce enough RNA to been seen using a special microscope.

Artist's image of DNA, from the National Institute of Health

Scientists all over the world are trying to find different ways of making step two faster and more efficient. One way is to use CRISPR, a gene editing tool that works like the find and replace function in a word document to change DNA in ways that have never been possible before. With cool names like SHERLOCK and DETECTR, these tests could get results in as little as 5 to 10 minutes by a process that may eventually be used to not only detect the virus but destroy its genetic material as well.

My book, CRISPR: A Powerful Way to Change DNA, comes out this fall from Annick Press. It will go to press before we know how much CRISPR will be used in the fight against COVID-19.

It’s exciting to think about how new technologies might stop future viruses through testing, treating and even developing vaccines. But the current pandemic is teaching us that the supply of basic stuff - masks, swabs, lab space and equipment – is really the most important thing of all.

Epidemics, Smallpox, and William Osler

By Gillian O'Reilly

These days, our minds are on epidemics (the rapid spread of disease to a large number of people in a given population within a short period of time) and pandemics (disease epidemics that have spread across large regions or worldwide).
 
One of my current projects is a book about the brilliant Canadian diagnostician and medical
educator Dr. William (Willie) Osler. Born in 1849 when people still thought diseases were
caused by bad air, Osler lived through the huge changes brought about by the discovery of
germs. There are several stories of his encounters with smallpox during his career.

Photo of William Osler from 1881 used with permission

of the Osler Library for the History of Medicine

In the nineteenth century, smallpox was a terrifying disease, often fatal. Survivors were left with bad scarring or blindness. Symptoms were fever, a rash, and characteristic pustules all over the body. Once diagnosed, smallpox patients had to be quickly isolated from other patients in a separate ward or hospital.
 
Vaccinations, successfully tested in 1796, had replaced variolation (an earlier form of inoculation used in Asia and Africa for centuries). Over the nineteenth century, widespread vaccination, sometimes mandated by law, had reduced the number of infections and deaths, but there were still regular outbreaks where vaccination rates were low.

In the spring of 1872 after his final year of medical school, Willie worked briefly at a hospital in Hamilton, Ontario. There he encountered a rare case of smallpox and drove the dying patient to mayor’s home to force the authorities to provide proper isolated accommodation for the man.
 

Quarantine poster image used with permission 

of the Osler Library for the History of Medicine

 
Montreal was one part of Canada where vaccination rates were low. Willie was teaching at McGill University during the smallpox epidemic of 1875-1876 and he took time to work in Montreal’s smallpox hospital, earning $600. Although he had been vaccinated (like all his siblings), he caught a mild case of the disease.
 
In those days, medical students learned mostly from lectures, rarely seeing patients or working in a lab. One of Willie’s innovations as a teacher was to make sure that his students had microscopes, so they could see and understand the diseases they were studying. The $600 he earned went to pay for microscopes.
 
Willie was one of the founders of the Johns Hopkins School of Medicine in Baltimore. When it opened in the fall of 1893, he at last had the medical school he wanted – a place where learning, hospital work and research were intertwined and where students could learn by doing. Willie led a weekly general clinic at the hospital, where he and students would see patients. 

By then, some diseases had become rare enough that many doctors and students had trouble diagnosing them. One resident proudly displayed what he thought was an interesting case of chicken pox to Osler and 30 or 40 students and doctors. When he threw back the sheet, a horrified Willie exclaimed, “My God, Futcher, don’t you know smallpox when you see it?” The patient was quickly isolated, the ward quarantined for six weeks and the students and staff hurriedly vaccinated.

In 1980, smallpox became the only human disease to be declared eradicated, thanks to a worldwide vaccination program in the 20th century.

More on William Osler and the history of medicine can be found at The Osler Library of the History of Medicine at McGill  https://www.mcgill.ca/library/branches/osler

The Osler Library Instagram page at https://www.instagram.com/oslerlibrary/  has a good drawing of emergency smallpox vaccinations being performed on American-bound trains from Montreal.