COVID-19 vaccine antibody responses in community-dwelling adults to 48 weeks post primary vaccine series

Sharon L Walmsley; Leah Szadkowski; Bradly Wouters; Rosemarie Clarke; Karen Colwill; Paula Rochon; Michael Brudno; Rizanni Ravindran; Janet Raboud; Allison McGeer; Amit Oza; Christopher Graham; Amanda Silva; Dorin Manase; Peter Maksymowsky; Laura Parente; Roaya Monica Dayam; Jacqueline Simpson; Adrian Pasculescu; Anne-Claude Gingras

doi:10.1016/j.isci.2023.106506

COVID-19 vaccine antibody responses in community-dwelling adults to 48 weeks post primary vaccine series

iScience. 2023 Apr 21;26(4):106506. doi: 10.1016/j.isci.2023.106506. Epub 2023 Mar 28.

Authors

Sharon L Walmsley^{1

2

3}, Leah Szadkowski^{4

3}, Bradly Wouters^{5

3}, Rosemarie Clarke¹, Karen Colwill^{6

3}, Paula Rochon^{7

3}, Michael Brudno^{8

3}, Rizanni Ravindran^{1

3}, Janet Raboud^{9

3}, Allison McGeer^{10

3}, Amit Oza^{5

3}, Christopher Graham^{11

3}, Amanda Silva^{12

3}, Dorin Manase^{12

3}, Peter Maksymowsky^{12

3}, Laura Parente^{13

3}, Roaya Monica Dayam^{6

3}, Jacqueline Simpson^{13

3}, Adrian Pasculescu^{6

3}, Anne-Claude Gingras^{6

3}

Affiliations

¹ Department of Medicine, University Health Network, University of Toronto, Toronto, ON, Canada.
² Toronto General Hospital Research Institute, University of Toronto, Toronto, ON, Canada.
³ University of Toronto, Toronto, ON, Canada.
⁴ Biostatistics Research Unit, University Health Network, University of Toronto, Toronto, ON, Canada.
⁵ Princess Margaret Cancer Center, University of Toronto, Toronto, ON, Canada.
⁶ Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, ON, Canada.
⁷ Women's College Hospital Research Institute, University of Toronto, Toronto, ON, Canada.
⁸ Department of Computer Science, University Health Network, University of Toronto, Toronto, ON, Canada.
⁹ Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada.
¹⁰ Department of Medicine, Mount Sinai Hospital, University of Toronto, Toronto, ON, Canada.
¹¹ Trillium Health Partners, Department of Medicine, University of Toronto, Toronto, ON, Canada.
¹² Department of BioInformatics, University Health Network, University of Toronto, Toronto, ON, Canada.
¹³ Health Care Human Factors, University Health Network, University of Toronto, Toronto, ON, Canada.

Abstract

We report a decentralized prospective cohort study of self-reported adverse events and antibody responses to COVID vaccines derived from dried blood spots. Data are presented for 911 older (aged >70 years) and 375 younger (30-50 years) recruits to 48 weeks after the primary vaccine series. After a single vaccine, 83% younger and 45% older participants had overall seropositivity (p < 0.0001) increasing to 100/98% with the second dose, respectively (p = 0.084). A cancer diagnosis (p = 0.009), no mRNA-1273 vaccine doses (p <0 .0001), and older age (p <0 .0001) predicted lower responses. Antibody levels declined in both cohorts at 12 and 24 weeks increasing with booster doses. At 48 weeks, for participants with 3 vaccine doses, the median antibody levels were higher in the older cohort (p = 0.04) with any dose of mRNA-1273 (p <0 .0001) and with COVID infection (p <0 .001). The vaccines were well tolerated. Breakthrough COVID infections were uncommon (16% older cohort, 29% younger cohort; p < 0.0001) and mild.

Keywords: Health sciences; Immune response; Immunology; Microbiology; Public health.