A study led by the UK Coronavirus Immunology Consortium finds that 98% of people aged 80 or over who had two doses of the Pfizer/BioNTech COVID-19 vaccine had a strong antibody immune response.
The research was carried out in collaboration with the University of Birmingham, Public Health England, and the UK Government’s Vaccine Taskforce, and has been published on The Lancet’s pre-print server and so has yet to be peer reviewed.
100 people aged 80 to 96 and living independently took part in the study. Each received two doses of the Pfizer/BioNTech vaccine three weeks apart. Researchers measured the immune response to the vaccine two weeks after their second dose.
98% of people in the study showed strong immune responses to the virus. 63% of participants developed T cell (cellular) responses to the virus, and these correlated with antibody responses. T cells are an important part of the immune system and are able to target specific viruses once recognised.
The research also found that participants who had previously been infected with COVID-19 naturally had a peak antibody response after just one dose of the Pfizer/BioNTech vaccination. In these participants, their antibody response remained 28 times higher even after the second vaccine dose.
Working with Public Health England at the Porton Down laboratory, the team showed original Wuhan virus variant was strongly neutralised in blood samples taken from participants after they had two doses of the Pfizer/BioNTech vaccine.
This immune response 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 are high enough to provide broad protection against this viral variant.
In summary, people aged 80 or over who have received two doses of the Pfizer/BioNTech vaccine have strong immune responses against the virus that causes COVID-19, and these are even higher when an individual has previously been infected with the virus. Responses are reduced against the P.1 variant, but they should still be effective at fighting the virus.
First author Dr Helen Parry, a National Institute for Health Research (NIHR) Academic Clinical Lecturer at the University of Birmingham, said of the study: “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/BioNTech 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 remains broadly effective against the P.1 variant, which is a variant of concern.”
Professor Paul Moss, Principal Investigator of the UK Coronavirus Immunology Consortium and Corresponding Author, added: “Our data also shows that for older people who have already had a natural COVID-19 infection, a single dose of the Pfizer/BioNTech 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.”
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.”