COVID-19 Rapid Tests : What You Need To Know!

Scientists are racing to develop COVID-19 rapid tests, which promise not only to be much cheaper, but also much faster, delivering results in a fraction of the time.

You may have seen some of them for sale too. Are any of these COVID-19 rapid tests the real deal? Let’s find out…

COVID-19 Rapid Tests : Fake Or The Real Deal?

 

COVID-19 Laboratory Tests : How Do They Work?

Laboratory testing for COVID-19, as per WHO recommendations, are Nucleic Acid Amplification Tests (NAAT) using real-time reverse transcription polymerase chain reaction (rRT-PCR)

They basically use RNA primers to target and cut specific segments of COVID-19 genes, so they can be amplified and then identified by RNA / DNA probes.

Different countries may look for different gene targets :

Country Institute Gene targets
China China CDC ORF1ab and N
Germany Charité RdRP, E, N
Hong Kong SAR HKU ORF1b-nsp14, N
Japan National Institute of Infectious Diseases, Department of Virology III Pancorona and multiple targets, Spike protein
Thailand National Institute of Health N
US US CDC Three targets in N gene
France Institut Pasteur, Paris Two targets in RdRP

Such laboratory tests usually take less than 24 hours to complete, although backlog of tests may result in longer wait times.

 

COVID-19 Rapid Tests : How Do They Work?

COVID-19 rapid tests cut down time and costs by avoiding the need for the cutting and amplification of nucleic acid samples.

Instead of looking for specific viral genes, these rapid tests look for IgM – the first antibodies our body makes to fight a new infection. Some rapid tests also look for IgG – the most abundant antibodies in the body.

That’s why they use blood samples, instead of nasopharyngeal swab (NP) or oropharyngeal swab (OP).

IgM vs IgG
Credit : MBL Life Science Japan

To “fish” for COVID-19 specific IgM and/or IgG antibodies, these rapid test kits use selected parts of the COVID-19 capsule proteins as antigens – bait – which are combined with colloidal gold as a marker.

When you drop a blood sample, COVID-19 antibodies (if present in the blood) will be “attracted” to the “bait” – the COVID-19 capsule proteins in the rapid test.

The antibodies will combine with the antigens, forming a visible, coloured compound which will appear as a red / burgundy line in the test strip.

 

COVID-19 Rapid Tests : What’s Available?

Now, there is no doubt that we will come up with COVID-19 rapid tests. It is what scientists are frantically working on. Look at how many have already been created :

COVID-19 Rapid Tests list

Some are already available for sale online :

They are certainly cheap – much cheaper than private COVID-19 testing available to those who are currently deemed not at risk.

 

COVID-19 Rapid Tests : Should You Use Them?

Now, these tests are no doubt convenient – allowing you to do it at home – and cheap. However, are they accurate and ready for use at home, by the public who are not trained in taking blood samples?

While health authorities are eager for such fast and cheap testing options, they are currently NOT advising people to use these COVID-19 rapid tests.

There will come a time when these COVID-19 rapid test kits are properly tested, and approved for use at home. Until then, it’s best to stay away…

Public Health England

Some manufacturers are selling products for the diagnosis of COVID-19 infection in community settings, such as pharmacies.

The current view by PHE is that use of these products is not advised:

  • some of these products look for virus while others look for the body’s immune response to the virus. Such tests are very rapid and can work on a range of specimens including serum, plasma or finger-prick whole blood
  • there is little information on the accuracy of the tests, or on how a patient’s antibody response develops or changes during COVID-19 infection. It is not known whether either a positive or negative result is reliable
  • currently there is no published evidence about the suitability of these tests for diagnosing COVID-19 infection in a community setting

Peter White, UNSW Virologist

The tests are not always as reliable as those currently being used. Because rapid test kits look for antibodies associated with the virus rather than the virus itself, they could record false negatives if used at the wrong time.

The question is how significant those limitations are. It depends really on how many true cases you detect. Does it detect every positive, or does it miss 5%?

Bill Bowtell, Infectious Disease Expert, Kirby Institute

In the end, anybody with anything to sell is in the market and their interest is to make the biggest claims.

I think that’s the case with a lot of the things that we’ll see coming onto the market. There’s uncertainty because it didn’t come to market after stringent testing, it came to the market because there’s a feeling of ‘my god we need it’.

In normal circumstances you wouldn’t touch it with a barge pole but this is what happens when there’s a crisis.

It is also notable that, as of 9 March 2020, China denied that they approved any COVID-19 test kits for use by the public at home :

The Beijing Medical Products Administration denied rumors that claimed that people can test for the novel coronavirus using a home testing kit and added there was no authorized home version of the test yet.

A so-called home testing kit went viral on WeChat, with the seller claiming the result would be visible 15 minutes after adding a drop of blood from one’s finger to the kit. The product was recommended for office buildings and schools to test those returning and isolated at home who could not access a medical test at the hospital.

According to the administration, samples carried by authorized testing kits can only be tested in polymerase chain reaction (PCR) laboratories or other medical institutes. There is no self-testing device yet and those sold on WeChat are fake.

 

COVID-19 : How To Keep Safe!

Here are a few simple steps to stay safe from COVID-19 :

  • Avoid suspected cases or disease hotpots, like hospitals, if possible!
  • Avoid public events and crowds
  • Keep our hands clean with soap or hand sanitiser
  • Keep our home, office, vehicles, etc. clean
  • If you need to wear a surgical mask, make sure you put it on and remove it properly!
  • Thoroughly cook your food, and boil water before drinking

Recommended : Soap vs Sanitiser : Which Works Better Against COVID-19?
Recommended : Surgical Mask : How To CORRECTLY Wear + Remove!

 

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