Pillar 9
Knowledge, Implementation and Training Team (KITT)

This study found positive associations between Post COVID-19 Condition (PCC), also known as Long COVID, and anti-spike (S), and anti-receptor binding domain (RBD) IgG concentrations, which were not statistically significant, and no association with anti-nucleocapsid (N) IgG concentrations. However, individuals with PCC had significantly higher neutralization efficiency, especially those that reported a deterioration in quality of life.

Key findings:

  • Similar proportions of individuals with PCC (66.7%) and infected controls (71.3%) tested positive for infection-acquired antibodies (anti-N). More individuals with PCC tested positive for anti-S (94.1%) and anti-RBD (95.1%) IgG, compared with controls (anti-S: 89.3%; anti-RBD: 84.4%). We observed similar differences among the non-vaccinated subgroup.
  • More individuals with PCC were efficient SARS-CoV-2 neutralizers (showing neutralization of ≥85% of SARS-CoV-2 spike protein) than infected controls. In both unvaccinated and vaccinated subgroups, median neutralization efficiency was somewhat higher among individuals with PCC than controls.
  • Individuals with PCC who reported deterioration in quality of life due to persistent symptoms had higher IgG titres and median neutralization efficiency. They also had a higher proportion of efficient neutralizers than those with PCC who did not report poorer quality of life.
  • Those with PCC were more likely to have allergies and to have sought medical help for their COVID-19 symptoms, as compared to individuals with past COVID-19 infection and no persistent symptoms ≥12 weeks post-infection.
  • Individuals with PCC, especially those who reported deterioration in quality of life, were more likely than infected-controls to seek medical help for COVID-19 symptoms and describe complex and enduring health needs long after initial infection.

The study, nested in a prospective study of over 1000 people followed-up at multiple time points for more than two years (Stope the Spread Ottawa / SSO), compared clinical and serological predictors among COVID-19 survivors with (n=102 cases) and without (n=122 controls) persistent symptoms ≥12 weeks post-infection. Participants ranged in age from 21-75 years old. Four primary serological predictors –- anti-N, anti-S, and anti-RBD IgG titres, and neutralization efficiency — were assessed, controlling for pre-determined clinical covariates.

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Clinical and serological predictors of Post COVID-19 Condition: Findings from a Canadian prospective cohort study. Erin Collins, Yannick Galipeau, Corey Arnold, Anne Bhéreur A, Ronald Booth, Arianne C. Buchan, Curtis Cooper, Angela M. Crawley, Pauline S. McCluskie, Michaeline McGuinty, Martin Pelchat, Lynda Rocheleau, Raphael Saginur, Chris Gravel, Steven Hawken, Marc-André Langlois, Julian Little. medRxiv.2023.07.29.23293334; https://www.medrxiv.org/content/10.1101/2023.07.29.23293334v1