COVID-19 postal kit study FAQs

We want to understand how many of our twins across the UK have developed antibodies against the virus that causes COVID-19, and how it may relate to symptoms experienced. We will analyse your blood sample to test it for the presence of these antibodies. This will help us understand the spread of the virus and how people’s immune systems may have reacted to it.

Doctors and scientists do not know yet whether antibodies offer any meaningful or long-lasting protection from re-infection against COVID-19. Antibodies are one tool that our bodies can use to fight off viruses, so it’s important that we understand as much as we can about how our body responds to COVID-19 and what kind of protection antibodies may offer.

The supplier of the blood collection kits has produced a video, available here. Please be aware that the same kits are used for other research studies, but we will only use your blood sample for COVID-19 research.

Yes please. We will do our best to test your blood for antibodies and give you a result, although this may not be possible if the volume of blood collected is too small. Do not attempt to prick your finger with anything other than the medical lancets provided.

We will be using what’s known as a ‘lateral flow test’ to analyse your sample. These tests look and work a bit like pregnancy tests, and allow us to quickly see whether there are antibodies present in your blood. We are using the same test device that is being used by many other studies across the UK as this will help us analyse all the data and compare results.

Our aim was to send you your antibody results within two weeks from receiving your blood sample back in the lab. There has been a slight delay and we are now aiming to start sending out results from this week (commencing 17th August) and over the following two weeks.

We will tell you whether you tested positive for IgG and/or IgM antibodies, negative or if the result was invalid.

The antibody test kit we are using has a sensitivity of 95.6% and a specificity of 95.2%.

Sensitivity is the ability of the test to identify positive cases correctly.

Specificity is the ability of the test to identify negative cases correctly.

We would like for all of our TwinsUK participants to complete the blood collection if possible. This will allow us to get a sense for how many of our twins across the UK have been exposed to COVID-19.

A small number of participants have also been sent an additional antibody self-test kit. This will help us compare and analyse our results with the results from other cohort studies that are using these test kits in the home.

There is a video available here which demonstrates how to carry out the test. Please be aware that the video was produced by another study using the same test kits.

If you received the additional antibody self-test kit, the online questionnaire will ask you to upload a photo of your antibody test stick. The easiest way is to take a photo using a smartphone. Please make sure the antibody test stick is within the black box outlined on page 15 of your instructions booklet.

To upload the photo to the questionnaire through your smartphone:

1. Open your online questionnaire link and navigate to the page that asks for the photo upload.
2. Tap the grey box that says “Drop files or click here to upload” and you will be able to navigate to your phone’s saved pictures.
3. Select the correct photo and it will be uploaded to your questionnaire.

To upload the photo to the questionnaire through a laptop or desktop:

1. Take a photo of your antibody test stick and email it to yourself.
2. Open the email on your laptop and desktop and save the attached image onto your computer.
3. Open your online questionnaire link and navigate to the page that asks for the photo upload.
4. You can now either drag and drop your image file into the grey box that says “Drop files or click here to upload”, or click on the box and you will be able to navigate through your files to select the correct image. When selected, it will be uploaded to your questionnaire.

On a smartphone:

1. Tap on the grey box (not the image) where you uploaded the original photo and you will be able to select another image from your saved pictures to replace the one previously uploaded.

On a laptop or desktop:

1. Click on the grey box (not the image) where you uploaded the original photo. You will then be able to select another image from your files to replace the one uploaded.
2. Alternatively, you can drag and drop the correct image into the grey box and it will replace the one already uploaded.

All participation in TwinsUK research is voluntary, and you are free to decline any element of any study.

If you have received an online link to your questionnaire:

If you do not wish to take part in the blood collection element of this study, please can we ask that you place all the materials back into the original envelope, strike through your address and write ‘Return to sender’. This will ensure the materials come back to us and we can re-use them. You are still welcome to take part in the questionnaire element of the study if you would like to do so.

If you have received a paper questionnaire:

If you do not wish to take part in the blood collection element of this study but are happy to complete the questionnaire, we’d be very grateful if you could. Once you have completed the questionnaire, please fold it in half and put it into the silver return envelope provided, along with the unused blood collection kit. From the label sheet provided, you will need to stick label C. Envelope Label (Back) on the back of the envelope, which is the reverse of the side which already has a large postage label on it. You can then post this in your nearest post box.

The antibody test produced a negative result. This means the test did not find antibodies in your blood. This means that you have not been infected with the virus, or at the time of testing, your body had not mounted a clear immune response against the virus that causes COVID-19.

You should continue to follow all guidance on self-isolation and social distancing as appropriate.

This means IgG antibodies against the virus that causes COVID-19 were found in your blood sample. This means you have likely had COVID-19 in the past and have developed antibodies against the virus that causes the condition.

It is important to note that doctors and researchers do not know whether having antibodies offers any meaningful or long-lasting protection against re-infection with this virus.

You should continue to follow all guidance on self-isolation and social distancing as appropriate.

We believe this means that you may have had or been exposed to COVID-19 recently and your body has mounted some level of immune response against the virus.

It is important to note that doctors and researchers do not know whether having antibodies offers any meaningful or long-lasting protection against re-infection with this virus.

You should continue to follow all guidance on self-isolation and social distancing as appropriate.

This means IgG and IgM antibodies against the virus that causes COVID-19 were found in your blood sample. This means you have likely had COVID-19 in the past and have developed antibodies against the virus that causes the condition.

It is important to note that doctors and researchers do not know whether having antibodies offers any meaningful or long-lasting protection against re-infection with this virus.

You should continue to follow all guidance on self-isolation and social distancing as appropriate.

This means we do not know whether you have antibodies or not, as the test did not work properly with the blood sample provided. This is most likely because your blood sample was delayed when in transit back to our lab, which affected the quality of the blood sample. At this time, we are unable to send out additional blood collection kits for further testing.

You should continue to follow all guidance on self-isolation and social distancing as appropriate.

This could be because: 

• The symptoms you experienced were the result of a flu or other standard bug, and you have not been exposed to COVID-19. 
• You may have been exposed to COVID-19 but at the time of testing, your body did not show a clear immune response to the virus. 

You should continue to follow all guidance on self-isolation and social distancing as appropriate. 

This may be because you were previously exposed to COVID-19 and developed a detectable level of antibodies, but by the time of this blood collection, the level of antibodies had declined to an undetectable level.

These results are private to you, although you are free to share them with others if you wish.  

Please bear in mind that these are research tests only, and we are not able to confirm a clinical diagnosis of a current or previous case of COVID-19 from them, as the results are from a King’s College London research lab, and not an NHS clinical-grade lab. 

More information about our research is available on our news page here and on our COVID Symptom app website here. We regularly share the latest news through our social media pages on Twitter and Facebook.