Dual dose of the Pfizer COVID-19 vaccine elicits strong antibody immune responses in older people

A University of Birmingham-led study supported by the UK Coronavirus Immunology Consortium has found that 98% of people aged 80 or over who had two doses of the Pfizer COVID-19 vaccine had a strong antibody immune response.

The research involved 100 people aged 80 to 96, who were living independently, and had received the Pfizer vaccine twice at three weeks apart. Immune measurements were taken two weeks after the second vaccination.

The largest and most complete independent study of older people’s immune response to Pfizer vaccination published to date, the study showed that, in 63% of participants, cellular T cell responses developed and correlated with antibody response.

The research also found that participants who had previously had natural COVID-19 infection had a peak antibody response after just one Pfizer vaccination. In these participants, their antibody response remained 28-fold higher even after the second vaccine dose.

Working with Public Health England at the Porton Down laboratory, the team showed live Wuhan virus was strongly neutralised in serum from blood samples taken from participants after they had two doses of the Pfizer vaccine.

The levels of neutralisation reduced 14-fold when tested against the P.1 COVID-19 variant that was first discovered in Brazil. However, the team are still hopeful that the levels of neutralisation shown is still sufficient to provide broad protection against this viral variant of concern.

First Author Dr Helen Parry, a National Institute for Health Research (NIHR) Academic Clinical Lecturer at the University of Birmingham, said: “With hopes pinned on COVID-19 vaccination playing a key role in bringing the current pandemic under control, it is essential that vaccine-induced immune responses are elicited effectively in people of older age, who we know are the most vulnerable group to COVID-19.

“However we also know that the quality of immune responses, including responses to vaccination, deteriorates with age.

“Although the Pfizer vaccine has shown good efficacy in those aged over 75, data on the immunological responses in those aged 80 years and over is lacking, including immune responses induced by the vaccine to the new COVID-19 variants of concern.

“Our research provides further evidence that the mRNA vaccine platform delivers a strong immune antibody response in people up to 96 years of age and retains broad efficacy against the P.1 variant, which is a variant of concern.”

UK Coronavirus Immunology Consortium Lead and Corresponding Author Professor Paul Moss, of the University of Birmingham, adds: “Our data also shows that for older people who have already had a natural COVID-19 infection, a single dose of the Pfizer vaccine strongly boosts the immune response. Indeed, in these people the levels of antibody remain quite a lot higher even after two doses of vaccine.

“While we need further research to understand this finding better, it’s important that everyone still follows NHS guidelines to get two doses of the vaccine, even if a person thinks they may have previously had COVID-19.

“Meanwhile, we found cellular immune responses were less complete and were detectable only in 63% of participants. It is not yet entirely clear how important these cellular responses are for protection or for supporting antibody responses in the longer term. However, this profile must be monitored and we will continue to study this cohort.”

The research, carried out in collaboration with Public Health England and the UK Government’s Vaccine Taskforce, has been published today on The Lancet’s pre-print server therefore is yet to be peer reviewed.

The study was partially supported by the UK Coronavirus Immunology Consortium, which is funded by UK Research and Innovation and NIHR.

Professor Moss continued: “Taking a collaborative approach to research through the UK Coronavirus Immunology Consortium and National Core Studies has allowed us to drive forward our knowledge at an incredible pace and build our understanding of how different components of the immune system respond to COVID vaccines. This knowledge will allow us to optimise vaccination protocols and maximise protection against SARS-CoV-2 within our population.”

Dr Joanna Jenkinson, Head of Infections and Immunity at the Medical Research Council, part of UKRI, said: “As the UK continues its rollout of vaccines against Covid-19, it’s critical we study the real-world impact of these vaccines at pace, especially amongst the groups most affected by the virus. This study from a group of world-leading immunologists who have come together under the UKRI and NIHR-funded UK Coronavirus Immunology Consortium, brings much welcome reassurance that the mRNA vaccine elicits a strong immune response in people over 80 years of age.”

The research specifically analysed the immune response to SARS-CoV-2 ‘spike protein’. For viruses like COVID-19 to survive, they have to get inside cells in order to replicate and build new virus particles and spread to other cells.

Coronaviruses are surrounded by a fatty membrane, and in order to gain entry to the inside of a cell they use something known as a ‘spike protein’ to fuse the membrane to a cell and take over the cell.

The spike protein of SARS-CoV-2 is stuck on a roughly spherical viral particle, projecting out into space, and ready to cling on to unsuspecting cells.

Given how crucial the SARS-CoV-2 spike protein is, some COVID-19 vaccines – known as mRNA vaccines and includes the Pfizer vaccine - have been designed to give instructions to our immune system to make our own version of the spike protein. Production of the spike inside our cells then starts the process of protective antibody and T cell production.

Notes to Editors

• To arrange interviews please contact Emma McKinney, Media Relations Manager, University of Birmingham, on +44 7815607157. Alternatively, contact the Press Office out of hours on +44 (0)7789 921165.
• The University of Birmingham is ranked amongst the world’s top 100 institutions, and its work brings people from across the world to Birmingham, including researchers and teachers and more than 6,500 international students from nearly 150 countries.
• Parry et al (April, 2021). ‘BNT162b2 vaccination in people over 80 years of age induces strong humoral immune responses with cross neutralisation of P.1 Brazilian variant.’ The Lancet.
• The research team is grateful for support from patients and staff at Lordswood Medical Group and Ridgacre House Surgery.
• The National Institute for Health Research (NIHR) is the nation's largest funder of health and care research. The NIHR:

1. Funds, supports and delivers high quality research that benefits the NHS, public health and social care
2. Engages and involves patients, carers and the public in order to improve the reach, quality and impact of research
3. Attracts, trains and supports the best researchers to tackle the complex health and care challenges of the future
4. Invests in world-class infrastructure and a skilled delivery workforce to translate discoveries into improved treatments and services
5. Partners with other public funders, charities and industry to maximise the value of research to patients and the economy
6. The NIHR was established in 2006 to improve the health and wealth of the nation through research, and is funded by the Department of Health and Social Care. In addition to its national role, the NIHR supports applied health research for the direct and primary benefit of people in low- and middle-income countries, using UK aid from the UK government.

• The UK Coronavirus Immunology Consortium brings together 20 UK immunology centres of excellence to research how the immune system interacts with SARS-CoV-2 to help us improve patient care and develop better diagnostics, treatments and vaccines against COVID-19. It is jointly funded by UK Research and Innovation (UKRI) and National Institute for Health Research (NIHR) and supported by the British Society for Immunology.