We are so grateful for the continued support and participation of all the trial volunteers who have taken part in COV001 and COV002 trials – this has provided critical information on the vaccine’s performance over time. Data from these studies are now being used by drug regulatory authorities around the world (including the MHRA, EMA and WHO) to support emergency authorisation of the use of the Oxford Astra-Zeneca vaccine. The vaccine is the most widely distributed of all Covid19 vaccines with over 550 million doses of the Oxford Astra-Zeneca used in more than 170 countries by July 2021 and tens of thousands of deaths prevented all around the world.
Here in the UK, Public Health England estimates that the national vaccination programme has so far prevented 14,000 deaths and around 42,000 hospitalisations. This work also shows that the Oxford Astra-Zeneca vaccine is 92% effective against hospitalisation caused by the ‘delta’ variant of the virus and is available here:
Emerging data from the Oxford vaccine trials now suggests that antibodies persist in the blood for up to a year even after a single dose of vaccine. In addition, increasing the interval between the first and the second dose from 4 weeks to 12 weeks increases the antibody level after the second vaccination, and further increases are seen with even longer dosing intervals.
A small number of trial participants also received a third dose of the Oxford Astra-Zeneca vaccine at about 30 weeks after their second dose, which was well tolerated and boosted antibody levels above those measured after the second dose.
These findings on antibody persistence, dose interval and booster doses have not yet been peer reviewed but are available here:
We are aware that some of our trial participants have asked if they need booster doses as they were vaccinated early in the trial or received different dose schedules. It is not yet known if a third dose is needed and there is no evidence that protection has declined in those who have been vaccinated. The JCVI (Joint Committee on Vaccination and Immunisation), the UK body that determines national immunisation, does not currently recommend a third dose of a COVID-19 vaccine to anyone who has already had 2 vaccine doses. We are currently working on studies to provide evidence on how boosters or new variant vaccines might help if they were needed. These data are being provided to the Government to inform their decision-making. Should further vaccination be recommended on the basis of this evidence, we will communicate this to you as soon as possible. Unfortunately, we are unable to give out immunology results to individual participants.
Further information for COVID-19 vaccine trial participants from the National Institute of Health Research can be found here:
By continuing with the final few clinic visits and continuing to inform us if they have symptoms of COVID-19, our trial volunteers are providing invaluable ongoing data about how long the vaccine offers protection, and also whether it offers protection against new strains of the virus.
Once again, we wish to thank all of the staff and volunteers who are part of the Oxford COVID-19 vaccine trials,
The Oxford Vaccine Group