This is a really good question and it is what the STRAVINSKY study is trying to answer. Below, you will find some more information on common asked questions about this topic and what we know so far. We also have a separate 'Frequently asked questions' page for questions on other aspects of STRAVINSKY study
What is a 'normal' COVID-19 antibody response?
Antibodies against SARS-CoV-2, which is the virus that causes COVID-19, can be measured in your blood. These COVID-19 antibody levels are at their highest (peak) about 28 days after vaccination or after infection with COVID-19 and then slowly fall. If your blood test was taken more than 28 days after your last COVID-19 vaccine dose or after you were ill with COVID-19, it is likely that your antibody levels will have fallen from their peak.
To give you an idea of how healthy individuals respond to COVID-19 vaccination, the average antibody level observed in our lab in blood samples taken 28 days after vaccination is 7,386 U/ml but we consider anywhere from 5,000 to 78,000 U/ml normal as 90% of healthy individuals fell within this range.
What does it mean if I have a negative COVID-19 antibody result?
A result less than 0.8 U/ml is reported as negative for SARS-CoV-2 antibodies. If you have a negative result, this means that your immune system has not been able to make antibodies in response to the COVID-19 vaccine. This can happen if someone has an underlying condition that affects their immune system or is on treatment that interferes with antibody production.
Just because you don’t have antibodies, it doesn’t mean you have had no benefit from the vaccine. The COVID-19 vaccine can also help your body produce protective T-cells (another part of the immune system); however, this is not measured routinely in the laboratory because the test is complex to run. We have learnt from laboratory studies, and also from real life situations, that some people without antibodies are able to recover from COVID-19 illness, experiencing only mild infections.
However, we are concerned that there is a risk the immune system will not respond optimally to infection without antibodies and this may lead to a more severe disease course. This isn’t always the case though and the COVID-19 disease course remains highly unpredictable on an individual basis. The combination of vaccines and new medicines have made a big difference to how unwell people become from COVID-19 and we know early treatment with anti-viral medication can improve how the infection is controlled in people who are immune vulnerable.
What does it mean if I have a low COVID-19 antibody response?
A result greater than 0.8 U/ml is considered positive for SARS-CoV-2 antibodies. However, we would expect healthy individuals to reach a level of at least 5,000 U/ml 28 days after vaccination. Your level may be lower than this just because your blood was tested a few months later from the ‘peak’ level at 28 days after vaccination or after falling ill with COVID-19. Alternatively, it could mean your immune system has not responded optimally to vaccination. This doesn’t mean that the vaccine hasn’t worked, and it is a key aim of this study to try and understand how much antibody is ‘enough’ to protect you against COVID-19 infection or severe infection.
What does it mean if I have a ‘normal’ COVID-19 antibody response?
A result greater than 5,000 U/ml at 28 days after vaccination is achieved by most healthy individuals. Some people who are considered clinically vulnerable can also produce antibody responses in this range and part of the study is to understand why some individuals remain vulnerable to COVID-19 infection even when they produce antibody levels that are within the normal range.
What does my antibody result mean if I am on immunoglobulin treatment?
Immunoglobulin products now contain significant amounts of SARS-CoV-2 antibodies. As a result, we are not able to differentiate between antibodies made by you and antibodies that are donated to you in the immunoglobulin and will not be able to easily assess your response to vaccination. However, it is still really important to include patients on immunoglobulin as a key aim of the study is to try and work out how much antibody is enough regardless of how you get it.
What if I want more information regarding my results and what they mean for me?
Please contact your local clinical team as they hold your medical records and can advise you individually. But remember, there continues to be much uncertainty about what the antibody levels mean in terms of protection against COVID-19, and this is exactly what STRAVINSKY is trying to answer.
Should I change what I do day-to-day because of my COVID-19 antibody level?
No! If you have read the information provided here (if you have a no, low or normal antibody response) you will have realised that there is still so much uncertainty as to what a COVID-19 antibody result means. Some people with no antibodies can become a little bit unwell with COVID-19 and have a mild disease course while some individuals with so called ‘normal’ antibodies can become very ill. As a result, we recommend that you continue to go about your day-to-day activities as you feel comfortable.
How long will it take for me to receive my results?
It can take up to 4 weeks for you to receive any results; this is because of the delivery times via Royal Mail, laboratory capacity, and recording of results. You will be sent all results via text message to the phone number you provided to the study team.
Will my results affect my care or treatment?
No. Your test result is not being communicated to your GP or hospital care teams. During our preliminary work, we asked patients whether we should send results to clinical teams and were given a clear direction not to do this due to the uncertainty of what a test result means. If you want to share your result with them, that is your choice.
Many NHS labs do have the test available if requested by doctors, but they will be looking at your result in context of your other tests and underlying health conditions. Many doctors are not requesting this test as there is no clear answer what a result means yet. No change to your care or treatment would ever be made on the result of a single antibody test.