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 120,000 deaths and around 230,000 hospitalisations. This work also shows that the Oxford Astra-Zeneca vaccine remains over 90% 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 are available here:
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. The government has currently advised people over 40 years, and those with underlying health conditions that put them at higher risk from coronavirus, should be offered a booster vaccine, and that there is no requirement to boost others, at this stage. There is currently no recommendation that healthy adults under the age of 40 or healthy children should be boosted, following two doses of the vaccine. Mild infection with COVID-19 is now common in double-vaccinated individuals whether or not they have been in trials. When these infections occur, they appear to boost immunity substantially.
Further advice from the JCVI (Joint Committee on Vaccination and Immunisation), the UK body that determines national immunisation, is awaited about whether there will be a further extension of boosting to younger age groups.
The JCVI advice on 3rd doses of COVID-19 vaccines is available here:
If you are invited to receive a third dose of a COVID-19 vaccine in the national roll-out, you should go ahead and receive a dose of the vaccine you have been offered. Please contact your study team should you have any queries.
Further information for COVID-19 vaccine trial participants from the National Institute of Health Research can be found here:
We are continuing to work on studies to provide evidence on how boosters or new variant vaccines may strengthen immune responses against COVID-19. These data are being provided to the Government to inform their decision-making.
By continuing with your final few clinic visits and continuing to inform us if you have symptoms of COVID-19, trial volunteers are providing invaluable ongoing data about how long the vaccine offers protection, and whether it offers protection against new strains of the virus.
Once again, we wish to thank all the staff and volunteers who are part of the Oxford COVID-19 vaccine trials,
The Oxford Vaccine Group