This is a summary, written by members of the CITF Secretariat, of:

Collins E, Galipeau Y, Arnold C, Bosveld C, Heiskanen A, Keeshan A, Nakka K, Shir-Mohammadi K, St-Denis-Bissonnette F, Tamblyn L, Vranjkovic A, Wood LC, Booth R, Buchan CA, Crawley AM, Little J, McGuinty M, Saginur R, Langlois MA, Cooper CL. Cohort profile: Stop the Spread Ottawa (SSO)—a community-based prospective cohort study on antibody responses, antibody neutralisation efficiency and cellular immunity to SARS-CoV-2 infection and vaccination. BMJ Open. August 16, 2022; doi:

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

A CITF-funded study’s cohort profile was published in BMJ Open, describing its study design, participant baseline characteristics, and ongoing data collection aimed at contributing data on effective SARS-CoV-2 immune responses conferred by infection and/or vaccination. The researchers highlight the need for longitudinal analyses of SARS-CoV-2 immune responses within diverse populations in response to ongoing vaccinations and emerging variants of concern (VoC). The study was led by Dr. Curtis Cooper (University of Ottawa) in collaboration with Dr. Marc-André Langlois (University of Ottawa) and Dr. Angela M. Crawley (The Ottawa Hospital Research Institute and University of Ottawa).

Participants were recruited from September 14, 2020 to September 28, 2021. Eligible participants were:

  • Over the age of 18 and living in the Ottawa region, and
  • At-risk of COVID-19 exposure due to occupation or health (“under surveillance”), or
  • Having a history of COVID-19 infection confirmed by a positive PCR or serology (“convalescent”).

Participants had to complete a survey, bloodwork, and questionnaire at baseline. In the following 10 months, the “convalescent” group (n=250) provided monthly blood samples for serum and saliva/sputum samples, along with bimonthly blood draws for plasma and peripheral mononuclear cells. Participants without a history of SARS-CoV-2 infection were enrolled in the ‘surveillance cohort’ (n=750). Both groups used home collection kits to submit monthly dried blood spots (DBS) for serology surveillance and saliva/sputum samples. At three- and 10-months post-baseline, both groups completed another questionnaire.

Those participating in an extended study involving 300 participants continued to attend blood draws every two months and completed additional questionnaires every six months for an additional 24 months.

The researchers are aiming to gather data on:

  • The detection of key SARS-COV-2 specific antibody isotypes (IgA, IgM, IgG);
  • The neutralization efficacy of antibodies (both SARS-CoV-2 and seasonal human coronaviruses);
  • SARS-CoV-2 specific T- cell responses.

The cohort was not diverse regarding age, race, and income status because mostly healthcare workers had been recruited by 2022. It is, therefore, not representative of the general Ottawa population. However, the study does have high participant retention and compliance and a good amount of pre-vaccination data for priority populations.

For their extended study, the researchers are aiming to:

  • Evaluate and compare the durability of SARS-CoV-2 immune responses over a longer timeframe,
  • Contribute data on VoC immunity and vaccine effectiveness,
  • Collect blood specimens from participants with pre-immune baselines for biobanking, and
  • Provide control data and specimens for other ongoing studies on SARS-CoV-2 vaccine immunogenicity in special populations.