Adaptive immune responses to two-dose COVID-19 vaccine series in healthy Canadian adults ≥ 50 years: a prospective, observational cohort study

Authors: Gaultier, Gabrielle N ;

McMillan, Brynn;

Poloni, Chad;

Lo, Mandy;

Cai, Bing;

Zheng, Jean J.;

Baer, Hannah M.;

Shulha, Hennady P.;

Simmons, Karen;

Márquez, Ana Citlali;

Bartlett, Sofia R.;

Cook, Laura;

Levings, Megan K.;

Steiner, Theodore;

Sekirov, Inna;

Zlosnik, James E.A.;

Morshed, Muhammad;

Skowronski, Danuta M.;

Krajden, Mel;

Jassem, Agatha N.;

Sadarangani, Manish

Source: Scientific Reports

Full text

: https://doi.org/10.1038/s41598-024-59535-0

Abstract

To evaluate immune responses to COVID-19 vaccines in adults aged 50 years and older, spike protein (S)-specific antibody concentration, avidity, and function (via angiotensin-converting enzyme 2 (ACE2) inhibition surrogate neutralization and antibody dependent cellular phagocytosis (ADCP)), as well as S-specific T cells were quantified via activation induced marker (AIM) assay in response to two-dose series. Eighty-four adults were vaccinated with either: mRNA/mRNA (mRNA-1273 and/or BNT162b2); ChAdOx1-S/mRNA; or ChAdOx1-S/ChAdOx1-S. Anti-S IgG concentrations, ADCP scores and ACE2 inhibiting antibody concentrations were highest at one-month post-second dose and declined by four-months post-second dose for all groups. mRNA/mRNA and ChAdOx1-S/mRNA schedules had significantly higher antibody responses than ChAdOx1-S/ChAdOx1-S. CD8 T-cell responses one-month post-second dose were associated with increased ACE2 surrogate neutralization. Antibody avidity (total relative avidity index) did not change between one-month and four-months post-second dose and did not significantly differ between groups by four-months post-second dose. In determining COVID-19 correlates of protection, a measure that considers both antibody concentration and avidity should be considered.

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Cite as

Gaultier, G., McMillan, B., Poloni, C., Lo, M., Cai, B., Zheng, J., Baer, H., Shulha, H., Simmons, K., Márquez, A., Bartlett, S., Cook, L., Levings, M., Steiner, T., Sekirov, I., Zlosnik, J., Morshed, M., Skowronski, D., Krajden, M., Jassem, A. & Sadarangani, M. 2024, 'Adaptive immune responses to two-dose COVID-19 vaccine series in healthy Canadian adults ≥ 50 years: a prospective, observational cohort study', Scientific Reports, 14, article no: 8926. https://doi.org/10.1038/s41598-024-59535-0

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DOI: https://doi.org/10.1038/s41598-024-59535-0

Repository URI: https://eprints.gla.ac.uk/325429/