Background: In several countries, extended interval COVID-19 vaccination regimens are now used to accelerate population coverage, but the relative immunogenicity of different vaccines in older people remains uncertain. In this study we aimed to assess the antibody and cellular responses of older people after a single dose of either the BNT162b2 vaccine (tozinameran; Pfizer–BioNTech) or ChAdOx1 nCoV-19 vaccine (Oxford University–AstraZeneca).
Methods: Participants aged 80 years or older, who did not live in a residential or care home or require assisted living, and had received a single dose of either the BNT162b2 vaccine or ChAdOx1 nCoV-19 vaccine were eligible to participate. Participants were recruited through local primary care networks in the West Midlands, UK. Blood samples and dried blood spots were taken 5–6 weeks after vaccination to assess adaptive immune responses using Elecsys electrochemiluminescence immunoassay and cellular responses by ELISpot. Primary endpoints were percentage response and quantification of adaptive immunity.
Findings: Between Dec 29, 2020, and Feb 28, 2021, 165 participants were recruited and included in the analysis. 76 participants had received BNT162b2 (median age 84 years, IQR 82–89; range 80–98) and 89 had received ChAdOx1 nCoV-19 (median age 84 years, 81–87; 80–99). Antibody responses against the spike protein were detectable in 69 (93%) of 74 BNT162b2 vaccine recipients and 77 (87%) of 89 ChAdOx1 nCoV-19 vaccine recipients. Median antibody titres were of 19·3 U/mL (7·4–79·4) in the BNT162b2 vaccine recipients and 19·6 U/mL (6·1–60·0) in the ChAdOx1 nCoV-19 vaccine recipients (p=0·41). Spike protein-specific T-cell responses were observed in nine (12%) of 73 BNT162b2 vaccine recipients and 27 (31%) of 88 ChAdOx1 nCoV-19 vaccine recipients, and median responses were three-times higher in ChAdOx1 nCoV-19 vaccine recipients (24 spots per 1 × 106 peripheral blood mononuclear cells) than BNT162b2 vaccine recipients (eight spots per 1 × 106 peripheral blood mononuclear cells; p<0·0001). Humoral and cellular immune responses against spike protein were correlated in both cohorts. Evidence of previous SARS-CoV-2 infection was seen in eight participants (n=5 BNT162b2 recipients and n=3 ChAdOx1 nCoV-19 recipients), and was associated with 691-times and four-times increase in humoral and cellular immune responses across the whole cohort.
Interpretation: Single doses of either BNT162b2 or ChAdOx1 nCoV-19 in older people induces humoral immunity in most participants, and is markedly enhanced by previous infection. Cellular responses were weaker, but showed enhancement after the ChAdOx1 nCoV-19 vaccine at the 5–6 week timepoint.
Funding: Medical Research Council, National Institute for Health Research, and National Core Studies.
|Journal||The Lancet Healthy Longevity|
|Early online date||12 Aug 2021|
|Publication status||Published - Sept 2021|
Bibliographical noteFunding Information: Medical Research Council, National Institute for Health Research, and National Core Studies.
This work was partially supported by National Core Studies Immunity and the UK Coronavirus Immunology Consortium funded by National Institute for Health Research/UK Research and Innovation. We thank Rory Meade, Rosie Laugharne, Tom Groves, Parjit Dhillon, Eleanor Brodie, and the patients and staff at Harborne Medical Practice, Northumberland House Surgery, New Road Surgery, Lapal Medical Practice and Wychbury Medical Group. We also thank Millie Manning, Danielle Sutherland, Tamsin Drury, and Alex Bray for their help in recruitment. We are grateful for support from Rajinder Jeet and Shahada Rahman Joli with phlebotomy services.
Open Access: This is an Open Access article under the CC BY-NC-ND 4.0 license.
Publisher Copyright: © 2021 The Author(s). Published by Elsevier Ltd.
Citation: Helen Parry, Rachel Bruton, Gokhan Tut, Myah Ali, Christine Stephens, David Greenwood, Sian Faustini, Sam Hughes, Aarnoud Huissoon, Rory Meade, Kevin Brown, Gayatri Amirthalingam, Ashley Otter, Bassam Hallis, Alex Richter, Jianmin Zuo, Paul Moss, Immunogenicity of single vaccination with BNT162b2 or ChAdOx1 nCoV-19 at 5–6 weeks post vaccine in participants aged 80 years or older: an exploratory analysis, The Lancet Healthy Longevity, Volume 2, Issue 9,
2021, Pages e554-e560, ISSN 2666-7568, https://doi.org/10.1016/S2666-7568(21)00169-0 (https://www.sciencedirect.com/science/article/pii/S2666756821001690)