Covid-19 testing

Covid-19 Testing

22/04/2020

Covid-19 viral infections were first identified in Wuhan, China in December 2019. Since then there has been a race to learn more about the illness, including how to diagnose it.

Swab Testing

Covid-19 symptoms include fever, cough, sore throat and loss of sense of smell. If you are experiencing symptoms we would recommend you are tested for Covid-19. We now have the ability to arrange swab tests for Covid-19. We will firstly arrange a phone or video consultation with one of our doctors, we will discuss your symptoms and how best to manage them. We will arrange for a courier to drop a swab test kit to your home and then collect it. We expect a laboratory result in 2-3 days. In the meantime if you have concerns about your symptoms, especially any shortness of breath or your symptoms are worsening after 7 days you should contact our clinic for help. We can arrange a home visit as needed for example to check oxygen saturations levels in the blood.

If one person in the household is confirmed to have Covid-19 we would recommend that other household members are tested. This is in keeping with the World Health Organisation advise to test and track every case.

What is a swab test?

We are using a Public Health England approved laboratory for our swab testing, they use a method called PCR (polymerase chain reaction). The laboratory is also supporting the NHS efforts to expand testing but they have confirmed they have ample spare capacity to allow private testing. The swab test kit uses a cotton swab to take a sample from the throat and nose. The kit contains full instructions on how to do this. We use a courier to drop and collect samples to enable a quicker result of the test for our patients. The swab test costs £175 for our Sage members, or £250 for pay as you go clients, including courier fees in the SW6 and SW10 areas. We would recommend performing a swab test in the first 7 days of illness to increase it’s accuracy. Swab tests can miss infections, for this reason it is important that if you are unwell and we suspect Covid-19 you and your household continue to follow the guidance on isolation. If the swab test is positive for Covid-19 this is highly accurate though and you can be highly confident that the illness is confirmed.

Antibody Testing

Many of our patients were unwell un February and March during the period when swab testing was limited and patients in the community were unable to be tested. We have been able to offer blood testing for patients who have had suspected Covid-19. We believe the current antibody tests we have available offer useful information to support patients who have had a recent suspected Covid-19 illness. We are only able to offer these tests as a tool to support the diagnosis in patients who have previous symptoms or exposure after a consultation to discuss symptoms and exposure as well as nature and accuracy of the tests in different settings. Hence, we only offer tests performed with a doctor, following a virtual consultation to assess your symptoms and possible exposure, to ensure you are appropriate to be tested and that you are fully informed and understand the nature and accuracy of the tests.

The tests should not be used until at least 14 to 21 days after symptoms start, when they are estimated as 99% accurate (by the manufacturer). They are CE marked and being used in Singapore and Australia. Detailed manufacturer information is available here. The tests should not be used to diagnose an early illness, this is a particular area for caution. We know there is a risk that patients who have a very mild or no symptoms may also test negative. A clinical study from Italy has been released, prior to peer review, on the pre-publication website medRxiv regarding the type of antibody test we have available. The authors of this study conclude that the test has “limited applicability for the diagnosis of SARS-CoV2″ but that the test “seems to provide useful information on the immunoreaction on individuals to the infection and, more importantly, it may detect previous exposure to the virus in currently healthy persons.” This means that the antibody test should not be used in early infections to diagnose COVID-19. However, it may be useful in demonstrating that someone has had COVID-19.

More recently, a team of scientists working at UC Berkeley in California on antibody testing in COVID-19 posted their results online in a paper prior to publication. They evaluated 10 tests including the type that we are using. Their paper demonstrated a 90% sensitivity and a 96% specificity for the tests that we are using when they are used at least 20 days following the onset of symptoms.

The tests are not suitable for home use. The MHRA have specifically warned against this. The tests require a very precise amount of blood 10 microlitres or 0.1ml and use of a further solution. We would advise against the purchase of kits from the internet, which may be inaccurate and very difficult to perform at home. Public Health England is working with companies to make a quick, easy home use test they have rightly have strict criteria. The tests would ideally need to be done at home, easily, give a simple easy to read result like a home pregnancy test. This kind of tests is not yet available. When the government does make these widely available we will let you know.

Regardless of any results, we MUST all continue to follow the government advice on social distancing. We do not yet know enough about the virus to be confident on immunity long term. Research in this area is ongoing worldwide and we will share updates as this progresses.

Due to the rapidly evolving science in this area, the tests cannot currently be used to grant any exceptions to the current government advice on social distancing.

We are working closely with our laboratory partners to be able to offer an ELISA test in the coming weeks. This ELISA test should provide more accuracy in the diagnosis of COVID-19.

Dr Lucy Hooper