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Bristol study finds third COVID-19 "booster" is associated with a substantial increase in antibodies

Press release issued: 24 January 2023

A national study involving Bristol’s Children of the 90s has found the "booster" vaccine led to a substantial increase in the antibodies that help protect against coronavirus. High levels of antibodies is associated with lower risk of severe infection.

The study, published today [24 January] in eLife, found the level of antibodies following a third vaccine, or booster, was around 10 times higher in the first weeks compared to those who had only received two vaccinations an average of six months earlier.

Researchers also found a third dose appeared to eliminate a key difference in antibody levels based on the type of vaccine received. While people who received the Oxford/AstraZeneca vaccine were more likely to have lower antibody levels than those who received Pfizer-BioNTech after one or two vaccinations, this difference was no longer present after a third vaccination.

The study involved researchers from the University of Bristol, King’s College London, University College London and several other institutions around the UK. These institutions form part of the National Core Study for Longitudinal Health and Wellbeing, which was set up by Sir Patrick Vallance, UK Chief Scientific Adviser, in October 2020 as part of the UK’s response to the COVID-19 pandemic.

Researchers analysed blood samples from 4,622 Children of the 90s participants and 4,739 participants from TwinsUK, another UK population cohort. According to the Bristol City Council website, 25% of 18 to 49 year-olds within the Bristol area remain unvaccinated for COVID-19.

Samples were tested to measure antibodies generated by vaccination and examine whether certain groups were more likely to have lower levels of antibodies. Lower levels are known to be linked to higher risk of coronavirus infection.  

Similar to previous research, the study found higher infection rates among participants with lower levels of antibodies after a first vaccination. However, researchers also found large increases in antibodies with each round of vaccination. Some groups of individuals had consistently lower levels of antibodies after vaccination, for example those who were “shielding” in the first year of the pandemic. Despite this, these individuals displayed a strong response to the booster. 

Principal Investigator of Children of the 90s and joint senior author, Professor Nic Timpson, said: "By responding to our antibody tests over the course of the pandemic, Children of the 90s participants have provided insight into the response to COVID-19 and the impact of the vaccination. It was fascinating to observe the dynamics of immune response and of course is reassuring to see how effective the booster jabs are. It’s also a chance to reflect on just how important our Children of the 90s participants are in enabling new research – this time with respect to the understanding and monitoring of infectious disease."

First author Dr Nathan Cheetham from King's College London said: "Our findings support a policy of a third (and now fourth) COVID-19 vaccination to boost antibodies and protect against COVID-19. This is especially true for people who had the Oxford/AstraZeneca vaccine for their first and second jabs. Our results also showed that some people are more likely to have a weaker response to vaccination than others, which we hope will be useful for policy-makers when considering any future COVID-19 vaccinations."

Professor Claire Steves, joint senior author from King's College London, said "We were particularly pleased to see that individuals at higher risk of severe infection still responded well to the booster vaccination. This is further evidence that coming forward for a booster vaccination is a good idea as COVID is still very much around."


'Antibody levels following vaccination against SARS-CoV-2: associations with post-vaccination infection and risk factors in two UK longitudinal studies' by Nic Timpson, Nathan Cheetham, Claire Steves et al. in eLife

Further information

About Children of the 90s
Based at the University of Bristol, Children of the 90s, also known as the Avon Longitudinal Study of Parents and Children (ALSPAC), is a long-term health research project that enrolled more than 14,000 pregnant women in 1991 and 1992.  It has been following the health and development of the parents, their children and now their grandchildren in detail ever since.  It receives core funding from the Medical Research Council, the Wellcome Trust and the University of Bristol.

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