COVID-19: Should I be tested? What you need to know about these precious tests

Governments around the world are fighting to contain and slow the rapid spread of the new coronavirus (137,445 infections and 5,088 deaths as of March 13). During this critical phase of the pandemic, social restrictions, confinement and screening tests are at the heart of the efforts.

Who should get tested?

Currently, there are two main cases for which a coronavirus screening test should be carried out: showing symptoms and / or having been in contact with an infected person.

The main symptoms of COVID-19, the disease caused by the coronavirus SARS-CoV-2, are: fever, dry cough and shortness of breath. These symptoms are very similar to those of the flu, so you need the advice of a doctor to determine if testing for the virus is necessary.

Local spread, sometimes without apparent signs…
Initially, the Centers for Disease Control and Prevention (CDC) recommended testing only people with symptoms who have been potentially exposed to the virus. However, to the surprise of public health officials, several of the first cases in the United States as well as in other countries, having tested positive for the virus, had no obvious exposure.

This development therefore suggests that the virus is transmitted locally, which means that it spreads easily from one person to another and / or that individuals may have transmitted the virus without experiencing obvious symptoms.

In response, on March 4, 2020, the CDC changed their recommendations to allow anyone with symptoms similar to COVID-19 to be tested as long as a doctor approves the request. Since the number of tests available is limited, the CDC encourages physicians to minimize unnecessary tests and to consider the risks of exposure to a patient before ordering them.

Screening is important because it quarantines infected patients and stops the spread of the virus.

As of this writing, there is no specific drug, vaccine, or treatment available for COVID-19, but that does not mean that screening tests are unnecessary. On the contrary, it allows you to define which patients are actually infected so that they can be quarantined in order to limit the spread of the virus.

Another advantage of carrying out a test is that it allows public health professionals to get a better idea of ​​the number of cases and the spread of the virus in the local or national population.

What does the test look like?

For a patient, the virus screening process is simple and can potentially take place almost anywhere: it usually involves collecting a swab deep into the nasal cavity to collect cells from the back of the nose.

The sample is then sent to a laboratory where it will be tested to determine whether the patient's cells are infected with the virus or not. The same process is used to take a sample for the flu test.

How does the screening test work?

Although collecting a sample is easy, it is much more complicated to determine whether or not a person is infected with SARS-CoV-2. In fact, the current method consists in looking for the genetic material of the virus (ie RNA) in the cells of a patient.

In order to detect the presence of RNA, laboratories perform a procedure called reverse transcription polymerase chain reaction. This method consists first of converting any viral RNA into DNA, before replicating it millions of times until there are enough copies for detection to take place.

If virus genetic material is found in the sample, then it is confirmed that the patient is infected and has SARS-CoV-2. It usually takes between 24 and 72 hours to get the results of a test.

At the start of the ramp-up of testing, accuracy raised concerns after a study found that 3% of tests in China were negative while the samples were actually positive. But this type of genetic test is generally very accurate (more than rapid flu tests), and the health benefits of the test outweigh the risk of error.

Are there enough tests?

The availability of tests can indeed be a problem. You should know that the latter requires a kit: either specialized equipment and personnel trained accordingly.

Integrated DNA Technologies, a company collaborating with the CDC, shipped 700,000 tests to commercial, university and health laboratories on March 6 in the United States. Quest Diagnostics and LabCorp, two large commercial test manufacturers, have started manufacturing their own test kits, available since March 9.

Many companies, hospitals and other institutions are now fighting to develop more tests to diagnose COVID-19. On March 10, 2020, Alex Azar, Secretary of Health and Social Services, announced that 2.1 million test kits are now available, of which more than one million have been shipped to certified laboratories. Millions more are expected to ship this week.

Will all potential patients have to be tested?

Realistically, it is technically impossible to test all people potentially affected by COVID-19. Therefore, most health officials believe it is important to prioritize screening for those who need it most, those at high risk: those over the age of 65, immunocompromised, those with other diseases (heart disease, lung disease, diabetes), individuals who have been in close contact with infected patients as well as those showing symptoms and having traveled to areas with high rates of infection.

As more tests become available, more people will be able to be tested.

There is also a need to develop faster tests, which do not require special equipment and personnel. Namely, these tests allow experts to better understand the progression of the epidemic and try to predict the impact of the virus on society.

Much remains to be learned about this new coronavirus…

One day, this pandemic will end. However, in the meantime, the population must absolutely take care to respect the measures imposed, in particular the fact of washing their hands correctly and regularly, coughing in the crook of the elbow and trying to minimize the risk of exposure and / or transmission of the virus to other people by limiting social activities.

There is still a lot to learn about this new coronavirus, and only time will tell if it will disappear from the human population (as SARS did in 2004) or if it will become, like the flu, a seasonal disease.


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