THE TRUEST OF TESTS

 

Despite an increasing number of people now being vaccinated against Covid 19, testing is still required in at least the following three cases: when returning to work at a regular office after an extended period of being based at home; when you are due in for elective surgery; or if you’re about to leave on an overseas trip.

The three most common testing options, according to the experts at Health.com, are the Molecular test (aka RNA or polymerase chain reaction [PCR] test), the Antigen test (aka rapid test), and the Antibody test (aka serology test or blood test). We look at how they work and the instances in which they may be offered to you in the section below:

SCREENING TYPES 1, 2, 3

Molecular test

This test, which is also called a nucleic acid amplification test (NAAT), is highly accurate for detecting an active infection – such as in the case where your doctor believes you currently have COVID-19. It may also be necessary to show the results of this test: if you are returning to work, college or school, plan on going into a retirement village or nursing home or need to prove your COVID-19 status before embarking on a flight. Your healthcare provider will collect mucus from your nose or throat, making use of a specialised nasopharyngeal swab, and turnaround time may vary from minutes to days or longer – so check this out beforehand so that you make your appointment in good time and are able to supply the test result, where and when it is needed. The depth to which these tests penetrate into your nose and/or throat is not pleasant, but at least the test is over in a couple of minutes.

 

Antigen test

Often called a point-of-care or rapid test, as a result of its rather speedy turnaround time, this inexpensively produced test tends to be used to screen a large group of people – such as in the airport before they board. While antigen testing is no more pleasant than molecular testing (the back of your nose and/or throat is still swabbed to collect a mucus sample), the result is available much more readily – often within 60 minutes or less. From an accuracy perspective, a positive antigen test is likely to be correct. However, this diagnostic check can miss an active infection, so if you have the main symptoms of COVID-19, but your antigen test reads negative, your healthcare provider is likely to order the molecular test (described above) so as to rule out the possibility of what’s referred to as a “false negative”.

Antibody test

Last but not least is the type of test that roots out coronavirus antibodies in your blood. Health.com describes these as “proteins your immune system produces to fight off a foreign invader, such as a virus”. What’s critical to understand about this particular diagnostic procedure is that it can tell you if you’ve been infected at some point in the past (even ages back) but cannot diagnose an active infection. This test is done by finger prick or drawing blood from a vein in your arm and is not recommended until at least 14 days after your C0VID-19 symptoms first come on. It can be extremely helpful in diagnosing an illness called Multisystem Inflammatory Syndrome in children because it is linked to the coronavirus. While researchers are not 100 per cent sure that a previous COVID-19 infection can provide any protection against a future one, the most recent investigations show that they do lessen the symptoms to some degree. This form of testing is also helpful, for example, in showing the prevalence of the infection in a particular population.

RIGHT ON THE MONEY

While the cost of your COVID-19 test may vary slightly according to where in the world – or at what type of venue – you have it done, the below prices will give you a pretty good idea. A PCR test is usually around £59.00 (US$89.01), but if you need the results within a couple of hours, you can expect to pay as much as £119.00 (US$163, 59). While not as readily accepted as the PCR test, especially when you are about to embark on some overseas travel, an antigen test will set you back a more affordable £35.00 (US$48,11). As far as antibody tests are concerned, you’ll need to fork out £65 (which includes your appointment and any follow-up advice) to show if you have any detectable antibodies in your blood as a result of a previous C0VID-19 infection. Note: it will not produce antibodies in response to your recent vaccination.

THE ACCURACY DEBATE

From the above information, it appears that the molecular test is the most accurate type of test available – but let’s first seek a little expert advice to confirm this. The verdict from the Centers For Disease Control and Prevention is that “laboratory-based tests, such as the PCR, have a generally high test sensitivity”. Yale Medicine’s infectious diseases expert, Dr Richard Martinello, concurs, adding: “PCR tests are considered the most accurate available. But because these tests are highly sensitive and specific, there is still the risk of a false positive.” While his colleague, Dr Sheldon Campbell, who specialises in pathology and microbiology, advises that “a PCR test is more likely (than any other type of test) to pick up an infection accurately”.

 

REMAINING UP TO SPEED

A last note on C0VID-19 is where to seek the latest and most reliable information. Cedars-Sinai.org

recommends, along with your major local newspaper, healthcare provider and neighbourhood hospital, that when seeking online advice, you prioritise the Centers for Disease Control and Prevention (CDC’s) dedicated C0VID-19 website and/or the World Health Organisation (the WH0’s) website. These latter two provide regular updates, dispel myths, share side effects, explain the need for vaccination cards, offer preventative measures and travel advice, and generally keep the global public up to date in the most accurate possible fashion. And that, of course, is the best we can hope for when confronted with a pandemic of this particular magnitude.

 

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