Finger prick antibody testing kits for detecting coronavirus ‘are as accurate as sophisticated lab analysis’ and have a 98 per cent accuracy race, a new study found.
Researchers from Guy’s and St Thomas’ NHS Foundation Trust and King’s College London examined a range of antibody tests as part of the study.
All of the commercial testing kits could tell if someone has or already had Covid-19 but they vary in terms of their performance in terms of overall accuracy.
All the tests examined by the team had a 95 per cent accuracy more than 20 days after coronavirus symptoms had shown – but performance varied before that point.
Antibody tests made by Accu-Tell, SureScreen and Spring came out top as they are able to provide accurate results within 20 days of symptoms appearing.
Co-author Jonathan Edgeworth said: ‘We found that some of the quick single-use kits are as accurate as our sophisticated laboratory technologies.’
Antibody tests made by Accu-Tell, SureScreen and Spring came out top as they are able to provide accurate results within 20 days of symptoms appearing
The team created a ‘rigorous comparison’ system that would allow doctors to more easily determine the best option for their hospital.
Unlike the throat and nose swab tests designed to say if someone is currently infected with the virus, antibody tests can tell if someone has had the virus.
For diagnosis later in disease, or in delayed-onset syndromes, antibody tests could form an important part of hospital diagnostic capabilities, authors say.
In the study the researchers developed a sensitive and specific antibody testing system and used it to conduct an unbiased comparison of the ten top testing kits.
They put the kits against each other in a head-to-head examination involving identical blood samples from patients admitted to hospital with Covid-19.
They then compared those tests to 50 pre-pandemic negative blood samples.
There was a broad range of performances among the tests, with the ability to identify those with the disease ranging from 82 per cent success to 100 per cent.
All gave the best results when used 20 days or more after the start of symptoms, with most tests reaching a sensitivity value greater than 95 per cent.
Unlike the throat and nose swab tests designed to say if someone is currently infected with the virus, antibody tests can tell if someone has had the virus
In addition, antibody levels were higher in individuals with severe illness compared to those with asymptomatic or mild disease.
When all commercial tests were compared, Accu-Tell, SureScreen and Spring demonstrated highest sensitivity at earlier time points, while maintaining a success rate in detecting the virus of 98 per cent or above.
These are ‘affordable, quick and easy to use, according to the team, who say if deployed appropriately they could be useful in healthcare settings.
‘Encouraged by these findings we are piloting them in the hospital to give doctors a quick reliable answer in a range of clinical settings,’ said Edgeworth.
The findings have been published in the journal PLOS Pathogens.
‘STRIP’ BLOOD TESTS FOR CORONAVIRUS WORK MUCH LIKE PREGNANCY TESTS
Simple blood tests for coronavirus, like Premier Biotech’s, work much like pregnancy tests.
After the sample of blood is collected, a technician injects it into the analysis device – which is about the size of an Apple TV or Roku remote – along with some buffer, and waits about 10 minutes.
The blood droplet and buffer soak into the absorbent strip of paper enclosed in the plastic collection device.
Blood naturally seeps along the strip, which is dyed at three points: one for each of two types of antibodies, and a third control line.
The strip is marked ‘IgM’ and ‘IgG’, for immunoglobulins M and G. Each of these are types of antibodies that the body produces in response to a late- or early-stage infection.
Along each strip, the antibodies themselves are printed in combination with gold, which react when the either the antigen – or pathogen, in this case, the virus that causes COVID-19 – or the antibody to fight are present.
Results are displayed in a similar fashion to those of an at-home pregnancy test.
One line – the top, control strip – means negative.
Two lines – the top control line and the bottom IgM line – in a spread-out configuration means the sample contains antibodies that the body starts making shortly after infection.
Two lines closer – control and IgG – together mean the person is positive for the later-stage antibodies.
Three lines mean the patient is positive for both types of antibodies.