Governance Organization

CHA – Children’s Hospital Academic Medical Organization

Project Title

CHA-21-010 – Persistence of Immunity in Children with SARS-COV-2 and Household contacts (PITCH Study)

Project Highlights

Despite the fact that the pandemic has been ongoing since March 2020, SARS-CoV-2 correlates of protection remain unknown. There is increasing but still incomplete understanding of long-term persistence of immunity and SARS-CoV-2 specific immunological memory. The majority of studies have focused on humoral immunity (antibody response) following COVID-19 infection and mostly in the adult population. Much less has been published on the role of T cells in the acute and convalescent phase of infection, despite its crucial role in antiviral immunity and vaccine development. Our proposed study on the longitudinal evaluation of T cell immunity after COVID-19 infection in children remains relevant, unique and much needed.

A strength of our study is the close collaboration with the CHAMO funded PATCH study: “Natural Evolution of Serum Antibodies in Children and Adults with SARS-CoV-2 and Household Contacts (PI Dr M Bhatt, Dr R Zemek, Dr Langlois). The PATCH study aims to understand the longitudinal antibody response (including neutralizing antibody) to SARS-CoV-2 infection in COVID-19 positive children and adults and their immediate household contacts. Our original protocol aimed to enroll 40 children and 20 adults with confirmed SARS-CoV-2 infection and recruited from the PATCH cohort (at similar time points in order to compare both antibody and T cell response), sampled over a one-year period. Given the rapid roll-out of COVID-19 vaccines, we plan to amend the protocol to be able to sub-analyze individuals according to their vaccination status. The majority of our pediatric study participants were unvaccinated at their initial study. Our immunological tests will be able to distinguish between immunity conferred by natural infection versus vaccine, and allow this to be evaluated over time.

The PATCH study has now completed enrolment (222 total households). Of those, 97 are index children and 125 are index adults. Our PITCH study started recruitment in early May 2021. To date, we have enrolled 38 children and 24 adults for a total of 62. Study visits for the first 2 time-points (T-2 and T-6 months from enrolment) have been completed, with the final time point (T-12 months from enrollment) scheduled in the mid to late 2022. The goal of our study remains the longitudinal measurement of T cell immunity following COVID-19 infection, with a particular focus in children and youth. Availability of vaccines will also provide us with an opportunity to compare the immune response of naïve and previously infected. We plan on focusing on the 5-11 year old group for whom there is very limited data. We are eager to start analyzing samples in early 2022.

The evaluation of the durability and persistence of the immune response to SARS-CoV-2 infection and the impact and contribution of COVID-19 vaccine is critical to better understand the COVID-19 clinical syndrome in children, to guide recommendations on COVID-19 immunization in children and inform public health guidance in school, daycare and other children and youth settings.


Public Health Measures and Society

Primary Project Lead for Contact

Anne Pham-Huy


Secondary Project Lead for Contact

Maala Bhatt


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