Hybrid immunity from SARS-CoV-2 infection and vaccination in Canadian adults: cohort study
- University of Toronto, Canada
- Lunenfeld-Tanenbaum Research Institute, Canada
- Unity Health Toronto, Canada
- Toronto General Hospital, Canada
- Angus Reid Institute, Canada
Abstract
Background: Few national-level studies have evaluated the impact of 'hybrid' immunity (vaccination coupled with recovery from infection) from the Omicron variants of SARS-CoV-2.
Methods: From May 2020 to December 2022, we conducted serial assessments (each of ~4000-9000 adults) examining SARS-CoV-2 antibodies within a mostly representative Canadian cohort drawn from a national online polling platform. Adults, most of whom were vaccinated, reported viral test-confirmed infections and mailed self-collected dried blood spots to a central lab. Samples underwent highly sensitive and specific antibody assays to spike and nucleocapsid protein antigens, the latter triggered only by infection. We estimated cumulative SARS-CoV-2 incidence prior to the Omicron period and during the BA.1/1.1 and BA.2/5 waves. We assessed changes in antibody levels and in age-specific active immunity levels.
Results: Spike levels were higher in infected than in uninfected adults, regardless of vaccination doses. Among adults vaccinated at least thrice and infected more than six months earlier, spike levels fell notably and continuously for the nine months post-vaccination. By contrast, among adults infected within six months, spike levels declined gradually. Declines were similar by sex, age group, and ethnicity. Recent vaccination attenuated declines in spike levels from older infections. In a convenience sample, spike antibody and cellular responses were correlated. Near the end of 2022, about 35% of adults above age 60 had their last vaccine dose more than six months ago, and about 25% remained uninfected. The cumulative incidence of SARS-CoV-2 infection rose from 13% (95% CI 11-14%) before omicron to 78% (76-80%) by December 2022, equating to 25 million infected adults cumulatively. However, the COVID-19 weekly death rate during the BA.2/5 waves was less than half of that during the BA.1/1.1 wave, implying a protective role for hybrid immunity.
Conclusions: Strategies to maintain population-level hybrid immunity require up-to-date vaccination coverage, including among those recovering from infection. Population-based, self-collected dried blood spots are a practicable biological surveillance platform.
Funding: Funding was provided by the COVID-19 Immunity Task Force, Canadian Institutes of Health Research, Pfizer Global Medical Grants, and St. Michael's Hospital Foundation. PJ and ACG are funded by the Canada Research Chairs Program.
Data availability
Ab-C data will be made available publicly through the COVID-19 Immunity Task Force (CITF) Databank. To access the data, please create an account on the CITF Databank portal and submit an application to use the data. Your application will be reviewed by the CITF Databank team. The data access procedure is described in detail at https://www.covid19immunitytaskforce.ca/wp-content/uploads/2022/11/data-access-diagram-en.pdf. This process is free of charge.Analytical code will be available on request in accordance with the Ab-C study's data governance plan. Please email the corresponding author, Dr. Jha at prabhat.jha@utoronto.ca to request the code. The CITF data team harmonizes data from multiple studies funded by CITF, including the Ab-C study. As a result, variable names and labels may change after the harmonization. To minimize confusion when using the code, it's best to have some contact with us when using the harmonized data.
Article and author information
Author details
Anne-Claude Gingras
Funding
COVID-19 Immunity Task Force (2021-HQ-000139)
- Anne-Claude Gingras
- Prabhat Jha
Canadian Institutes of Health Research (EG2-179433)
- Prabhat Jha
Pfizer Global Medical Grants (61608943)
- Prabhat Jha
St. Michael's Hospital Foundation
- Prabhat Jha
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Eduardo L Franco, McGill University, Canada
Ethics
Human subjects: The Ab-C study was approved by the Unity Health Toronto Research Ethics Board (REB # 20-107 and 21-213). All participants provided informed consent to be included in the study.
Version history
- Received: October 23, 2023
- Accepted: June 20, 2024
- Accepted Manuscript published: June 25, 2024 (version 1)
Copyright
© 2024, Brown et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Hybrid immunity from SARS-CoV-2 infection and vaccination in Canadian adults: cohort study
eLife 13:e89961.
https://doi.org/10.7554/eLife.89961
Further reading
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- Computational and Systems Biology
- Epidemiology and Global Health
The chemical composition of foods is complex, variable, and dependent on many factors. This has a major impact on nutrition research as it foundationally affects our ability to adequately assess the actual intake of nutrients and other compounds. In spite of this, accurate data on nutrient intake are key for investigating the associations and causal relationships between intake, health, and disease risk at the service of developing evidence-based dietary guidance that enables improvements in population health. Here, we exemplify the importance of this challenge by investigating the impact of food content variability on nutrition research using three bioactives as model: flavan-3-ols, (–)-epicatechin, and nitrate. Our results show that common approaches aimed at addressing the high compositional variability of even the same foods impede the accurate assessment of nutrient intake generally. This suggests that the results of many nutrition studies using food composition data are potentially unreliable and carry greater limitations than commonly appreciated, consequently resulting in dietary recommendations with significant limitations and unreliable impact on public health. Thus, current challenges related to nutrient intake assessments need to be addressed and mitigated by the development of improved dietary assessment methods involving the use of nutritional biomarkers.
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- Epidemiology and Global Health
Background:
Comorbidity with type 2 diabetes (T2D) results in worsening of cancer-specific and overall prognosis in colorectal cancer (CRC) patients. The treatment of CRC per se may be diabetogenic. We assessed the impact of different types of surgical cancer resections and oncological treatment on risk of T2D development in CRC patients.
Methods:
We developed a population-based cohort study including all Danish CRC patients, who had undergone CRC surgery between 2001 and 2018. Using nationwide register data, we identified and followed patients from date of surgery and until new onset of T2D, death, or end of follow-up.
Results:
In total, 46,373 CRC patients were included and divided into six groups according to type of surgical resection: 10,566 Right-No-Chemo (23%), 4645 Right-Chemo (10%), 10,151 Left-No-Chemo (22%), 5257 Left-Chemo (11%), 9618 Rectal-No-Chemo (21%), and 6136 Rectal-Chemo (13%). During 245,466 person-years of follow-up, 2556 patients developed T2D. The incidence rate (IR) of T2D was highest in the Left-Chemo group 11.3 (95% CI: 10.4–12.2) per 1000 person-years and lowest in the Rectal-No-Chemo group 9.6 (95% CI: 8.8–10.4). Between-group unadjusted hazard ratio (HR) of developing T2D was similar and non-significant. In the adjusted analysis, Rectal-No-Chemo was associated with lower T2D risk (HR 0.86 [95% CI 0.75–0.98]) compared to Right-No-Chemo.
For all six groups, an increased level of body mass index (BMI) resulted in a nearly twofold increased risk of developing T2D.
Conclusions:
This study suggests that postoperative T2D screening should be prioritised in CRC survivors with overweight/obesity regardless of type of CRC treatment applied.
Funding:
The Novo Nordisk Foundation (NNF17SA0031406); TrygFonden (101390; 20045; 125132).
