Covid Blood Test FAQ

Coronovirus Antibody Blood Test FAQ Leaflet

This leaflet is intended for patients of Dr Kumar-Beurg who have already discussed and decided to go ahead with Covid-19 antibody blood test and it serves as a reminder about advice that is usually given to patients during consultation. If you do not understand the following or feel it doesn’t apply to you then please ignore it or contact us for clarification.


What Test is Done?

We offer both the nasopharyngeal PCR swab and the the antibody blood test to detect if a patient is “currently suffering from” or has “ever been exposed to” Coronovirus Covid-19. This test is the Antibody Blood Test which tells if a patient has been exposed to Coronovirus more than 14-21 days ago. The test detects the presence of immunoglobulins in the blood (IgG); these are the molecules that are made by the immune system to fight an infection when it is first encountered. The presence of Coronovirus specific IgG indicates that the patient has been exposed to the infection (1).


Who Should Do the Test?

The antibody test is best done 14-21 days after the first symptom(s) of Coronovirus. These include fever, cough, loss of taste/ smell, diarrhoea/ abdominal pain/ loss of appetite and fatigue/ “brain-fog”. However there is clear evidence that some people (possibly many people) can have the Coronovirus infection without suffering any symptoms (2) so it’s almost impossible to judge by a person’s symptoms alone.


Is the Test Accurate and Reliable?

The one word answer is – Yes.

It should be noted that the subject of antibody testing is controversial in the UK because the Government, NHS and PHE have not agreed and approved any of the antibody tests for use by the NHS.

Bedside testing kits – similar to pregnancy test kits – have claimed to give instant results (based on IgM and IgG antibodies), however, there are questions about the accuracy of these tests. Therefore, we recommend using a lab-based test.

The blood is processed by The Doctors Laboratory (TDL) which is a very well established service just off Harley Street in London that we have used for several years  – it’s the largest Private Practice lab in the UK and also does extensive testing for the NHS including ones for Coronovirus.

The actual lab machinery is made by Abbott which is again based in the UK and is one of the leading global brands for medical equipment and it’s the same machine that’s been used regularly for years for similar tests. The Abbott test has been in use around the world including the USA (3) since the start of the Covid pandemic and was awarded a CE mark and approved for European-wide use on 29th April (4) & (5).

The test is described as having a 100% sensitivity (which means that it will detect the antibody in all the blood samples that have it) and 99.5 specificity (it will give the correct answer, negative in 99.5% of the blood samples that are free of antibody). This means that the lab technique has a negligible/ zero false negative rate (ie if there are antibodies in the sample then they’ll be detected).

In the real world there are also other factors that can affect the accuracy of lab tests (such as immonusuppresive disease or medications) and one of the major sources of controversy at Governmental level seems to be the impact of false positives when the actual prevalence of infection in the population is relatively low (6).


How Do I Take the Sample From Myself?         << Self Test Antibody Blood Tests Not Currently Available >>

The test is a fingerprick blood sample that uses a self-administered, spring-loaded lancet rather than a needle & syringe phlebotomy sample to draw the blood.

Before you take the sample it’s helpful (but not necessarily essential) to;

  • Make sure you’re well hydrated, have had plenty of water to drink beforehand
  • Make sure you’re warm and relaxed
  • Hold your hand(s) in a bowl or sink full of warm water for 5-6 minutes and
  • Wash your hands with soap & dry them before doing taking the sample.

When you use the lancet it’s preferable to apply it to the side of your finger, not the main fingerpad.

If you can stand up while taking the sample and keep the bottle on a low table while you milk the finger for blood then that’s usually easier – but – if you feel even slightly faint or unsteady then please make sure you’re seated to do the test.


How Do I Return the Sample to the Lab?

To prepare the sample for return;

  • Make sure that your sample bottle has been labelled with your name, date of birth and the test date
  • Put the sample bottle back into the folding plastic bottle holder and put the bottle holder back into the clear plastic bag. 
  • If possible then please write the date of collection on the request form and …
  • Make sure the request form is inside the yellow-white plastic mailing bag.
  • Put the clear sample bag with the specimen into mailing bag and seal it shut.
  • The mailing mag already has the lab’s address and postage paid stamp on it.

To dispatch the bag you can either;

  1. Send it using the pre-paid Royal Mail service. Because of service disruptions since the UK went into lock-down I think it’s better to use an alternative but if you decide to post the sample then I strongly recommend taking the sample to a post office in the morning and sending it as guaranteed next-day delivery. 
  2. Use a courier such as or 0800 373737. 
  3. Use a taxi service (if they agree) such as Uber or a local minicab firm. 


How Long Does it Take to Get the Result?

The sample takes 2-3 days to process and the result will be sent to you by email.

What Does a Negative Result (“Anti-SARS CoV 2 IgG Result: NOT Detected”) Mean?  

A negative test result completed in the correct time frame would suggest you have not previously suffered from COVID-19 – there are very few exceptions to that. This means that if you’re exposed to the Covid virus in future then you may develop the infection. 

What Does a Positive Result (“Anti-SARS CoV 2 IgG Result: IgG Detected”) Mean?  

If the result says “2019-nCoV IgG Detected ” then that means that you have had the Coronovirus infection.  

The national guidance and instructions are being frequently updated so please make sure to read the up-to-date information on the links below which are available in multiple languages (7,8,9). The main points you need to know are;

  1. A positive test result indicates you have had the virus.
  2. It is not yet known whether this grants any future immunity to the virus which means you may be able to get the virus more than once.
  3. Whether or not previous exposure confers immunity, we don’t know how long the antibodies will remain in your system. Other coronavirus antibodies, such as ones that cause the common cold, usually stay in the body for 1-2 years. 
  4. If you get worse then you should seek further medical attention. You can contact us but please be aware that Cloud Health only offers routine booked appointments and does not offer an unscheduled or Out Of Hours Service. If you need more urgent care than we can provide then please telephone 111 or 999 as appropriate. Please do not go to a GP surgery, a Walk-in Centre or an A&E Department unless you’ve been given special instructions over the phone and told exactly where to go.
  5. There is no requirement or recommendation to do contact tracing or testing at this time but your household members should seek medical advice if they start to show any symptoms of Coronovirus.
  6. Covid-19 is a “notifiable disease” and all Doctors making a diagnosis are legally required to inform Public Health England (PHE). We will also send a copy of positive results to your registered NHS practice and recommend that you contact them (by phone/ online) to discuss the result with them.








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