Antibody & PCR Testing
Greenfields currently offer two types of testing for SARS-CoV-2 (COVID-19):
- PCR testing (for those with active disease symptoms)
- Antibody testing (for those who have had symptoms in the past or may have been exposed but have no symptoms)
For patients in the UK our laboratory partner is ArminLabs in Germany, which has a long history of testing for viruses, bacteria and parasites.
Read more about the two types of testing below for the UK and US.
The PCR testing method (Polymerase Chain Reaction) is a genetic test for the specific RNA (ribonucleic acid) of the coronavirus SARS-CoV-2. PCR is a nucleic acid amplification technique, which are amongst the most reliable COVID-19 tests for diagnosing current infection. These tests can be used to directly detect the SARS-CoV-2 virus in people who are currently infected persons, using a throat swab, nose swab or throat lavage. All tests for COVID-19 should be performed in coordination with a healthcare provider.
The sample required is 1 x throat lavage tube with 50ml salt water solution. Taking the sample at home is a quick and easy procedure. If you are suitable for testing, the kit comes with full instructions and will be sent to you at home. A courier will be ordered the day before taking the sample, to collect the kit and take it to ArminLabs for testing. The results will be reported by the lab on the day the sample is received.
When you are infected with a virus the body responds by making specific immune system memory proteins (antibodies) to attack invaders such as bacteria or viruses. After infection with the virus these proteins remain in the blood. A test can determine who has already had the virus or been exposed to it by searching for levels of antibodies.
There are three types of antibodies produced by the body that can be tested, which take different times to become evident in the blood, and stay in the blood for different amounts of time:
- IgM is the first antibody produced upon infection
- IgA is produced by the mucous membranes, and is present after IgM can be detected
- IgG is a longer-lasting antibody produced after IgM
N.B. There is currently no evidence that having antibodies to SARS-CoV-2 confers immunity from future infection with the virus (although the development of a vaccine would presuppose that this would be the case), and if so, for how long immunity might last, as there is a possibility that the virus might mutate into a form which is not recognised by the antibodies.
Why would you want to get a test for SARS-CoV-2?
- Differentiates SARS-CoV-2 from other acute pulmonary infections such as the influenza virus
- Provides diagnostic assistance in the event of new infections
- Can document a current or previous infection approximately 2 - 3 weeks after the onset of symptoms
- Provides Documentation of an immune reaction and possible immunity
If you require a sample kit to test for active coronavirus infection this can be sent to your home after a video or phone consultation. We will order a courier to collect the sample kit and deliver it to the laboratory the next day, your test results will be sent to you as soon as we receive them, and followed up with a video or phone call to discuss the results.
2 - 3 weeks after the onset of symptoms and 4 - 5 weeks after exposure, almost 100%. of people produce detectible antibodies. If you require a sample kit for coronavirus antibodies for past infection you will need to come in to the clinic to give a blood sample. This will either be tested in the clinic or sent to the laboratory for testing.
In certain circumstances you may wish to get tested by both PCR and antibody methods. In this case where you may have active infection we can make arrangements to carry this out in your own home.
Ordering a PCR Test
If you have symptoms which could be associated with coronavirus COVID-19 do not come in to the clinic, we will send you a sample kit to use at home.
Symptoms may include the following:
- Fever (above 39ºC/102ºF)
- Persistent cough
- Phlegm with or without blood
- Muscle aches or headaches
- Fatigue or exhaustion
- Loss of or change in taste or smell
- Shortness of breath or difficulty breathing
- Sore throat
- Runny nose
- Jaw or facial pain
- Loss of appetite, nausea or vomiting
Call the clinic on 01227 454 848 to make a video appointment or phone consultation to discuss your symptoms and suitability for testing. If you are a candidate for coronavirus PCR testing we will arrange delivery of the test kit for yourself and any other members of your household, and a courier collection to take the samples to the lab.
When the results are ready a video appointment or phone consultation will be arranged to explain your results to you and what you should do next.
Ordering an Antibody Test
Antibody testing can be done 2-3 weeks after the onset of symptoms, or 4 -5 weeks after exposure.
- We will go through the COVID-19 symptom checklist during a video or phone consultation for antibody testing for the following people:
- Patients who have previously tested positive via a PCR swab test
- Patients who have previously had COVID-19 symptoms
- Those from high risk groups who have had contact with patients infected with the COVID-19 virus
- If a past infection is suspected with no signs of current infection, we can do the testing in the clinic or take a blood sample and send it to the laboratory to check your immune response
- We can take a fingerprick blood sample and do the SARS-CoV2 IgG/IgM rapid test in the clinic to get results within 15 minutes. We will provide you with a copy of the test form with a positive or negative test result
- We can take a blood sample from your vein and send the sample to the laboratory to run the SARS-CoV2 IgG/IgA ELISA antibody test. You will get an official medical certificate from ArminLabs with a positive or negative result for COVID-19
- We will interpret your antibody test results and discuss the implications with you
Older people, and patients with underlying medical conditions (such as hypertension, cardiac issues or diabetes, cancer, another active infection and/or those suffering from immunosuppression) may be subject to a more severe course of COVID-19. Self-isolation, with limited exercise and a suboptimal diet during this period may lead to further deficiencies. In these cases ArminLabs recommends checking additional parameters, including:
- CD3+/CD56+/CD57+ cell count - these are natural killer cells involved in fighting viruses and other infections
- Zonulin (intestinal permeability)
- Vitamin D3
Call the clinic on 01227 454 848, email us for a call back or use our online booking system to make a video appointment or phone consultation to discuss your symptoms and suitability for testing.
PCR Testing Technical Details
For initial diagnostic testing for COVID-19, the World Health Organisation (WHO) and the US Centers for Disease Control and Prevention (CDC) recommend collecting and testing an upper respiratory specimen. The nasopharyngeal specimen is the preferred choice for swab-based SARS-CoV-2 testing, and throat swabs (posterior pharyngeal swab, avoiding the tongue) are also recommended in addition. The collection of a combined nasopharyngeal and pharyngeal swab is uncomfortable, complicated to perform, and should only be taken by trained professionals. ArminLabs, in cooperation with the test manufacturer, has established and validated an equivalent method of taking a sample which can be performed by yourself at home. Since a high concentration of viable SARS-CoV-2 virions can be found in the throat and sputum within the week after the symptoms first appear, ArminLabs also offers PCR testing using a throat lavage solution to be used during this time. A preprint (not yet peer-reviewed) paper found that saliva is more sensitive for SARS-CoV-2 detection in COVID-19 patients than nasopharyngeal swabs for PCR testing.
Antibody Testing Technical Details
In a corrected proof of a paper published in Clinical Infectious Diseases, on patients who tested negative for PCR, the average duration of IgM and IgA antibody detection was 5 days, and in these cases testing for IgM was found to be more accurate than PCR testing.
The body needs some time (usually around 2 - 3 weeks) to produce antibodies. The average time to produce antibodies is 13 days after the onset of symptoms – 50% of patients have no detectable antibodies within the first 12 days, but antibodies are detectable in almost 100% of people 20 days after the onset of symptoms.
Antibody testing is done using a blood sample, either in the clinic (instant test for IgG and IgM) or at the laboratory. In the clinic test the IgM antibodies have a relative sensitivity of 85% and a relative specificity of 96%. The IgG antibodies has a relative sensitivity of 100% and a relative specificity of 98%. This test was developed at the German Leibniz Institute, is CE certified, and IVD registered and validated. The instant test shows no cross reactivity with influenza antibodies.
To test antibodies for the novel SARS-CoV-2 coronavirus In the laboratory, ArminLabs uses the SARSPLEX system, an innovative multiplex ELISA (Enzyme-Linked Immunosorbent Assay) diagnostic kit. SARSPLEX incorporates both the spike (S1 subunit) antigen, and the nucleocapsid protein (N) for better sensitivity, specificity and robustness in diagnosis. In addition, SARSPLEX tests for immune responses of IgM, IgG and IgA against this novel virus. When combined, the SARSPLEX test has a specificity and sensitivity of around 100%.
Our Testing History
At Greenfields Canterbury we have been offering private testing for health conditions, as well as being an agent for sexual health testing companies. We have performed blood draws for many years, and we have carried out in-clinic instant testing for chlamydia, gonorrhoea, herpes simplex, syphilis and HIV since 2018. We currently use surface and air sterilisation procedures to reduce the chance of infection when coming in to the clinic as a patient, as well as personal protective equipment.
Testing in the US
In the US, COVID-19 PCR and Antibody tests are being carried out by the CDC compliant labs, Sonora Quest Laboratories, Labcorp and Great Plains Laboratory. As a licensed primary care physician, Dr Jacqueline Greenfield can evaluate you for testing and interpret your results during a Telemedicine consultation. She can advise you on whether your family members should also be tested. Contact Dr. Greenfield via her US website drjacquie.us.