For the past few months, companies from all over the world have been working to develop rapid and effective COVID-19 screening instruments. The French NG Biotech announced this week that it has developed a serological test that can be interpreted in 15 minutes.
Serological technology detects not the presence of the virus in the body, but that of the antibodies produced by the immune system in response to the infection.
Dr. Gaston De Serres, doctor-epidemiologist at the National Institute of Public Health of Quebec (INSPQ) and professor of epidemiology at Laval University, mentions that serology is already used for the detection of diseases such as measles.
Gaston De Serres, doctor-epidemiologist at the INSPQ
Photo: Radio-Canada
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<q data-attributes = "{" lang ": {" value ":" fr "," label ":" Français "}," value ": {" html ":" The majority of cases will be detected by tests serological and we will look, at that time, in the patient's blood, for antibodies that are specific to measles. We're going to look for a type of antibody (IgM or IgG) which is a marker of an acute infection “,” text “:” The majority of cases will be detected by serological tests and we will look, at that time, in the patient’s blood, for antibodies which are specific with measles. We are going to look for a type of antibody (IgM or IgG) which is a marker for an acute infection “}}” lang = “en”>The majority of cases will be detected by serological tests and we will look, at that time, in the patient’s blood, for antibodies that are specific to measles. We’re going to look for a type of antibody (IgM or IgG) which is a marker of an acute infection, explains Dr. De Serres in an interview with Radio-Canada.
The first reaction of an organism in the presence of an infection such as a virus or bacteria is to produce IgM antibodies (immunoglobulins M). The IgM are then gradually replaced by antibodies IgG (immunoglobulins G).
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A proven concept
In the case of the new coronavirus, the challenge for manufacturers of screening instruments is to rapidly develop a reliable serological test to detect a disease that was known to most people just a few months ago.
The problem is to identify which antibodies really correspond to COVID-19 and to have a test which is reliable, replicable, valid, etc. So that’s the part asking for the book, but […] it’s a concept that is really well proven, that holds up and that generally works very well
, specifies the doctor-epidemiologist.
If the tool has a good sensitivity to detect cases, to be positive in people who are sick, who has good specificity, therefore which is negative for people who do not have COVID-19, and who is fast, sure it would be extraordinary.
Currently, public health laboratories in Quebec, Canada and elsewhere in the world mainly use nucleic acid amplification tests (TAAN or PCR in English) to screen for the new coronavirus.
Nucleic acid amplification tests are the primary method of screening for COVID-19.
Photo: Reuters / Dado Ruvic
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Unlike serological tests, TAAN detect the presence of the virus in the body. From the sample taken from the patient, amplified (or copied) targeted nucleic acid sequences in order to detect the presence of the disease. A reliable and precise technique, but not the fastest.
These are cycles: we heat, we cool, we heat, we cool [le prélèvement] so that the nucleic acid particles in the virus multiply until they become detectable. So that, obviously, takes a while
, specifies Gaston De Serres.
“It would be really fantastic”
Dr. François Desbiens, director of public health for CIUSSS de la Capitale-Nationale, believes that the development of a reliable serological test would greatly speed up the detection of COVID-19. Isolation measures for affected patients would be more targeted and more effective.
To secure, isolate the right person, it would be really fantastic […] because right now, there are people who isolate themselves two or three days without knowing if they are positive or not
, says Dr. Desbiens in an interview with the host of the Téléjournal Quebec, Bruno Savard.
It would be ideal, because it would be much faster than the test we currently have.
Canadian Health Minister Patty Hajdu recently approved an emergency order to speed up the import and sale of medical devices to diagnose, treat or prevent COVID-19.
COVID-19 screening clinics have mushroomed in recent weeks.
Photo: Radio-Canada / Ivanoh Demers
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Health Canada prioritizes instruments using nucleic acid technology, but companies wishing to market a serological test in Canada will be able to submit their product for review.
As of April 2, 16 companies, mostly Chinese and American, have submitted a request to Health Canada to license a screening device using serological technology.
To view requests for authorization of diagnostic instruments for COVID-19 received by Health Canada, click on this link (New window).
Attentive Quebec
For its part, the Department of Health and Social Services (MSSS) from Quebec says that it is evaluating all the options to ensure that the province maintains sufficient analytical capacity. The Ministry recalls that no blood test to detect COVID-19 is still available in the country.
<q data-attributes = "{" lang ": {" value ":" fr "," label ":" Français "}," value ": {" html ":" Le MSSS is well aware that certain tests have been approved in France and the United States, which does not mean that they are approved for Canada by Health Canada “,” text “:” The MSSS is well aware that certain tests have been approved in France and the United States, which does not mean that they are approved for Canada by Health Canada “}}” lang = “fr”>The MSSS is aware that some tests have been approved in France and the United States, which does not mean that they are approved for Canada by Health Canada, spokesman Robert Maranda said in an email to Radio-Canada.
An employee in a laboratory specializing in the COVID-19 nucleic acid test.
Photo: Associated Press
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He adds that massive use
of technology by one country could lead to supply difficulties for other countries.
This is one of the elements to be assessed before proceeding with the use of new technology
, specifies Mr. Maranda.
Better comprehension
Serological tests may also help determine the percentage of people who get COVID-19 after coming into contact with the disease. Scientists would then be better able to assess the spread of the coronavirus, notes Gaston De Serres.
If we pass a TAAN to an immune person, the result will be negative, even if they have been exposed to the coronavirus. A serological test, however, will detect the presence of antibodies in his body.
<q data-attributes = "{" lang ": {" value ":" fr "," label ":" Français "}," value ": {" html ":" When [le coronavirus] meets people who are immune, well, obviously it cannot be transmitted. So if we had a large proportion of people who never developed symptoms, never a virus detectable by TAAN, it could help make the epidemic affect far fewer people and end much earlier than we think at the moment “,” text “:” When [le coronavirus] meets people who are immune, well, obviously it cannot be transmitted. So, if we had a large proportion of people who never developed symptoms, never a virus detectable by NAAT, it could contribute to making the epidemic affect a lot less people and end much earlier than we think for the moment “}}” lang = “fr”>When [le coronavirus] meets people who are immune, well, obviously it cannot be transmitted. So if we had a large proportion of people who never developed symptoms, never a virus detectable by TAAN, it could help make the epidemic affect a lot less people and end much earlier than we think at the moment, mentions Dr. De Serres.
He added in this regard that the percentage of people infected in epidemic outbreaks like the region of Wuhan, in China, will be revealing for the future.
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