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
Affiliations
Sharon L. Walmsley
Department of Medicine, University Health Network, University of Toronto, Toronto, ON, Canada; Toronto General Hospital Research Institute, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada; Corresponding author
Leah Szadkowski
Biostatistics Research Unit, University Health Network, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Bradly Wouters
Princess Margaret Cancer Center, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Rosemarie Clarke
Department of Medicine, University Health Network, University of Toronto, Toronto, ON, Canada
Karen Colwill
Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Paula Rochon
Women’s College Hospital Research Institute, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Michael Brudno
Department of Computer Science, University Health Network, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Rizanni Ravindran
Department of Medicine, University Health Network, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Janet Raboud
Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Allison McGeer
Department of Medicine, Mount Sinai Hospital, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Amit Oza
Princess Margaret Cancer Center, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Christopher Graham
Trillium Health Partners, Department of Medicine, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Amanda Silva
Department of BioInformatics, University Health Network, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Dorin Manase
Department of BioInformatics, University Health Network, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Peter Maksymowsky
Department of BioInformatics, University Health Network, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Laura Parente
Health Care Human Factors, University Health Network, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Roaya Monica Dayam
Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Jacqueline Simpson
Health Care Human Factors, University Health Network, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Adrian Pasculescu
Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Anne-Claude Gingras
Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
Summary: 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.
