As the lockdown gently eases and the Prime Minister changes the slogan from Stay Home and Stay Safe to Stay Alert, Control the Virus, Save Lives and those who can go to work safely should go to work, is it really safe to ease the lockdown now? What are the latest updates on Covid-19 testing? As schools prepare to re-open on 1st June after the half term break, how safe is it for our children and the teachers? If all non-essential shops are to re-open from 15th June, are we ready? Will there be a second peak? How safe is it really for us to gently ease out of the lockdown? Should we all get tested? Do we expect our places of work to offer testing? Should all people-facing staff be tested? Does having antibodies mean immunity? If so, how long would we have immunity for? Coronavirus is an RNA virus meaning it can and will mutate, does that mean we will have a new strain every year? Where are we on the search for a vaccine? There are a million more questions we are all eager to know. Let’s unravel some together.

Finger-prick test accuracy?

At the very beginning of the pandemic and the lockdown, when nothing else was available, there was a place for finger-prick antibody testing to see if we have had the infection (IgG), are having the infection (IgM), are a silent or asymptomatic carrier, or have never been infected at all. In the recent weeks, with the development of new and better testing, finger prick tests are generally out.

But some doctors and clinics are still offering finger-prick test at £99 or less including the PHE approved Abbott and Roche test, is it safe? They even have home kits.

The short answer is NO. No finger prick test is PHE approved. The Abbott antibody test for Coronavirus is a serology test, meaning we have to take your blood from your vein, and send it to an approved lab for testing and it is inaccurate to use finger-prick blood nor is that method approved by Abbott or PHE. The test requires 0.6ml of your blood, and finger-prick blood is not appropriate nor is it approved, after all, a finger prick will only provide less than 0.1ml of blood, which is not nearly enough. The test therefore must be performed by a doctor who will take the blood and also provide correct interpretation and management.

Abbott and Roche Antibody Testing?

Abbott and Roche are the two latest giant pharmaceutical companies to provide antibody testing, cited by the manufacturers, the government and Public Health England as 100% accurate based on its initial study. Both are similar types of testing. The antibody test looks for IgG antibodies, which are the antibodies that are generated following the maturation of the antibody response (in essence after the infection). In this case, the antibody test looks for the SARS-CoV-2 IgG antibodies.

 Abbott Test?

The SARS-CoV-2 IgG test is an CMIA (Chemiluminescent Microparticle Immuno Assay: an advanced serological diagnostic technique) assay manufactured by Abbott Laboratories. The assay is listed as CE marked. It is designed to detect immunoglobulin class G (IgG) antibodies to the nucleocapsid protein of SARS- CoV-2 in serum and plasma from patients with signs and symptoms of infection who are suspected of coronavirus disease (COVID-19) or in serum and plasma of subjects that may have been infected by SARS-CoV-2. The result will be expressed as either positive or negative for IgG antibodies present in the sample.

Roche Test?

The Elecsys Anti-SARS-CoV-2 assay is an ECLIA assay manufactured by Roche Diagnostics GmbH. The assay is listed as CE marked. As per the manufacturer’s information, the assay uses a recombinant protein representing the nucleocapsid (N) protein of SARS-CoV-2.

The tests contain two controls: ACOV2 Cal1 containing human serum, non-reactive for anti-SARS-CoV-2 antibodies, and ACOV Cal2 containing human serum reactive for anti-SARS-CoV-2 antibodies. The analyser automatically calculates the cut off based on the measurement of ACOV2 Cal1 and ACOV2 Cal2. The result of a sample is given either as reactive or non-reactive as well as in the form of a cut off index (COI; signal sample/cut off). The results can be interpreted as follows:

Numeric Result Result Message Interpretation
COI <1.0 Non-reactive Negative for anti- SARS-CoV-2 antibodies
COI >1.0 Reactive Positive for anti- SARS-CoV-2 antibodies

 

100% accuracy?

Over the last few days, scientists and experts have questioned the veracity of such claims being “100% accurate” and as game-changers in the identification of past infection with COVID-19. These claims were based on studies undertaken by Public Health England (PHE), but the release of these statements preceded any official study reports being made available, and thus their validity could not be scrutinised at the time.  These reports have now been released and it is possible to check the veracity of the “100% accuracy” claim.

What’s accuracy?

The accuracy of a test relates to whether or not it makes errors: whether there are individuals with the disease who wrongly get negative test results, and whether there are individuals without the disease who wrongly get positive test results. 

False Positive? False Negative?

Both Roche and Abbott tests make no or very few false positive errors – they only very rarely wrongly state a non-COVID-19 sample as showing antibodies to COVID-19.

Both tests sometimes miss detecting COVID-19 in samples which are from infected patients (false negative).

Let’s look at some actual facts and figures.

For the Roche test, 93 samples with COVID-19 were tested, of which 78 (84%) gave positive test results, meaning 16% were missed.  

For the Abbott test, 96 samples with COVID-19 were tested, of which 90 (94%) gave positive test results, meaning 6% were missed.  

Therefore, both the tests cannot be described as 100% accurate.

When to get tested?

In our opinion, the antibody test should only be used 14 days after the onset of symptoms for greater accuracy. The performance of the test increases with the time since onset of symptoms.  This is expected as it takes some time after infection for antibody responses to build up and be detectable.  The study from PHE showed that 25% of COVID-19 samples taken between 11 and 20 days after onset of symptoms wrongly tested negative, 21% between 21 and 30 days and 5% after 30 days.  These figures are based on even smaller samples and have large uncertainty in them.  The trend with time was not so evident in the samples tested by Abbott.

What is R? How does it affect us?

R = Reproduction Rate

The reproduction number means the disease’s ability to spread. 

It’s the number of people that one infected person will pass the virus on to, on average

Measles has one of the highest numbers in town with a reproduction number of 15 in populations without immunity. It can cause explosive outbreaks.

The new coronavirus, known officially as Sars-CoV-2, has a reproduction number of about 3.

How is R calculated?

R cannot be calculated at the point of infection but, instead scientists work backwards. Calculating the number of people dying, admitted to hospital or testing positive for the virus, estimates how easily the virus is spreading. 

This gives us a picture of what the R number was two to three weeks ago. Regular testing of households should soon give a more timely estimate.

Why is a number above 1 dangerous?

If the reproduction number is higher than one, then the number of cases increases exponentially! But if the number is lower, the disease will eventually die out, as not enough new people are being infected to sustain the outbreak.

Quarantine all UK arrivals?

Simply setting a quarantine for 14 days, we feel may be a tad too much given the easing of the lockdown rules as we strive to regain some sort of normality. Perhaps, all arrivals should have routine medical checks upon entering the country; an antibody test as well as a PCR swab to rule out an active infection. They should be in a quarantine for 2 days at a maximum whilst awaiting results. Symptomatic patients, those who tested positive on PCR swabs must then be isolated whilst those with positive IgG and a negative swab should be allowed to enter, although those with negative IgG and have no symptoms should be closely monitored i.e. being able to be contacted should they develop symptoms etc. This will not only help our economy greatly; it will also cut out the unnecessary overly strict quarantine rules.

Table: Dr Terry’s Clinic suggested UK arrivals plan (c) Dr Terry Clinic

Symptoms

IgG Antibody

PCR Swab

Action

NO

Positive

Negative

Clear to enter

NO

Negative

Negative

Clear to enter but closely monitored on tracing

YES

Negative

Negative

Isolation 14 days

YES

Negative

Positive

Isolation 14 days

NO

Negative

Positive

Isolation 14 days

Our thoughts and Corporate Testing

We, at Dr Terry’s Clinic firmly believe that at-risk and vulnerable individuals must still be kept isolated despite the easing of the lockdown rules currently. We also believe that hand hygiene and social distancing must still be observed despite re-opening of non-essential shops. There are, however, ways to decrease our risk of getting the infection, passing the infection and causing a second surge of the infection. Taking on-board good medical advice, good hand hygiene, social distancing and antibody testing can prevent us from having a second surge of the infection and increasing our R rate.

We feel that antibody testing can somewhat give us a better idea of the infection and help control the spread of Coronavirus. We feel that people will be more reassured knowing that the people they interact with have been tested and those who are symptomatic must be further tested and isolated to curb the spread.

We have now introduced a corporate health side to our clinic to offer businesses and employers advice on Covid-19 management and a safer environment for employees as well as the general public. We offer bespoke advice, strategies, management plans, anti-viral tools, hygiene stations, antibody testing, PCR swab testing as well as regular monitoring tailor-made to suit your business need, to ensure a stronger, healthier and more productive work force. As a small business ourselves, we understand how vital it is to have a healthy and productive team. In this economy of course we recognise that this must be done within the budget, but as well as the core services, we will also provide luxury extras for your employees such as nutritional and wellness advice. Our team is ready to help get us all back on our feet and make this nation great again.

For more information or if you have any queries, please email us on manager@DrTerry.com

Much love,

Dr. Terry and Team