The virus responsible for COVID-19 outbreak has swiftly become a global pandemic. One of the factors that has been under scrutiny, is the amount of testing that has been undertaken. This guide is designed to provide some of the background to COVID-19 testing, what to look for in a good test and what a test can tell us.
Detection of COVID-19
In order to confirm other signs and symptoms of COVID-19, a test for the active infection, or for the body’s response to it, can be measured. In the case of COVID-19 the genetic sequence of the virus was worked out early in the pandemic and this provided a specific viral footprint that could be detected when the body responds to an infection. This infection can remain in the body for around 7 days before the signs and symptoms appear. At this stage the virus is usually live and producing some specific antibodies (called immunoglobulins) that are best detected by a swab method and laboratory analysed by a method called PCR.
As the infection progresses the body makes additional antibodies and in particular one called IgG. This is produced in detectable levels some 2-3 weeks after the initial infection and provides the ability to create a longer-term immunological memory. This can be tested from a blood sample and is commonly used to identify earlier infections.
Therefore, the choice of which test is relative to the time from the initial infection and the probability of COVID19 infection is made form a combination of test and symptom data.
COVID-19 Antibody Testing
Testing of a blood sample for antibodies will identify an earlier or previous infection of the COVID-19 virus. These are taken as blood samples in clinics for maximum accuracy of results. Samples are sent to the testing laboratories for analysis & results. The blood sample testing is often referred to as antibody testing. It is important to remember this type of testing will identify previous infection and will not detect the active infection found in the first 2-3 weeks.
At some Nomad locations, we can now provide in-clinic testing for COVID-19 antibodies. You will visit a Nomad clinic, following strict PPE & distancing guidelines, where an expert nurse will take a blood sample. Your sample will be sent to our laboratory for analysis to determine whether COVID–19 antibodies are present. We’ll get your results in 2-3 working days when we’ll send you a link to your secure results & some guidance documents on what the results mean.
To request in-clinic COVID-19 Antibody Testing, complete the form below & we’ll be in touch soon to book an appointment.
Nomad use the MHRA-UK criteria when advising our clients and unfortunately, we are currently unable to supply self- test kits with a high enough standard of accuracy, due to the lack of availability. This standard may be higher than other country’s test kits.
COVID-19 Infection Testing
Detection of the active virus is undertaken by a swab test and analysed in a licensed laboratory using a technique called a PCT test. This is a swab test of the nose and throat which can be done at home with the swab sample. This sample can then be posted directly to the laboratory for analysis and results. It is important to remember this type of test will identify an active virus infection that usually is detectable in the first 2-3 weeks only.
The standards of accuracy of testing are set by a UK government agency, the Medicines Healthcare Regulatory Agency (MHRA), who have published a document which sets the standards for self-test kits. The standards of the tests currently on the market give varied levels of responses, none of which have yet met the MHRA standard. To date these tests have been found to have a lower accuracy and the ones which are currently available can only produce unacceptable levels of false readings.
Frequently Asked Questions – COVID-19 Testing
What is the difference between IgG and IgM antibodies?
The body provides 2 responses to an infection that produces antibodies at different times to protect the body. The initial IgM antibodies are produced within a few days of the infection and last for around 2 weeks. During this time, the longer lasting IgG antibodies are produced, which provide a “memory” to hopefully help prevent re-infection.
What standards should I be looking for when assessing the purchase of a self-test kit?
The MHRA sets standards for the immunoglobulins mentioned above and the levels of false results. Each immunoglobulin should have a sensitivity (false negative- telling someone they haven’t had the infection when they have) and a specificity (false positive- telling someone they have had an infection when they haven’t). For each immunoglobulin, the specificity and sensitivity (not accuracy) should have individual values greater than 98% and not averaged values. Currently none of the self-test or home-test kits meet the minimum standards and Nomad will not being using type of test.
What are the consequences of using a test kit with lower levels than the MHRA standard?
Of the tests available for rapid or self-use most do not have individual values of greater than 98%. Nomad determine this is unacceptable as they may introduce too many false negative or false positive results. The consequences of a test kit reporting a value of say 90% would mean that 1 in 10 tests would be incorrect. When this is scaled up to the government daily target of 100,000 this becomes 10,000 a day, which will influence the rate of infections in the community and possibly return people to work who were still infectious or people thought they had protection but were still able to contract the infection.
What does a test kit with a CE mark of Conformity mean?
The CE mark of conformity is a manufacturer’s self-declaration they have made test kits using their own manufacturing processes to EU standards. This is not a licence of accuracy or evidence of meeting MHRA standards or tested by the EEA. Nomad wishes to use test kits that have been tested and endorsed by a fully regulated authority to MHRA criteria.
For further information, please visit the following:
MHRA- Specification criteria for serology point of care tests and self-tests
BBC News
https://www.bbc.co.uk/news/world-asia-india-52378265
Find out more about the myths and facts surrounding Coronavirus by reading this blog.
Request In-Clinic COVID-19 Testing
No Comments
Be the first to start a conversation