# Canadian Creutzfeldt-Jakob disease incidence remained stable during the coronavirus disease (COVID-19) pandemic

## TL;DR

Canadian CJD incidence remained stable during the pandemic despite increased testing, showing no link to COVID-19.

## Contribution

Demonstrates that CJD surveillance in Canada remained consistent and unaffected by the pandemic.

## Key findings

- CJD incidence rates were stable during the pandemic despite increased EP-QuIC test submissions.
- Demographics and molecular subtypes of sCJD were largely consistent across periods.
- A higher proportion of females were tested during the pandemic, and sCJD MV1 prevalence declined post-pandemic.

## Abstract

Healthcare disruptions imposed by the coronavirus disease (COVID-19) pandemic and possible biological links between SARS-CoV-2 and prion misfolding might influence the prevalence or characteristics of Creutzfeldt-Jakob Disease (CJD). This report investigates the potential impact of the COVID-19 pandemic on Canadian CJD diagnostics and surveillance from 2016–2025.

Canada-wide CJD diagnostic findings from end-point quaking induced conversion (EP-QuIC) cerebrospinal fluid (CSF) assays were compared across three periods: pre- (2016-01-29 – 2020-02-28), during (2020-03-01 – 2022-09-30), and post-COVID-19 (2022-10-01 – 2025-09-29). Presented are incidence rates and distributions of biomarker abundances, case demographics, CJD molecular subtypes, and disease durations.

While EP-QuIC test submissions increased during the pandemic, CJD incidence was unaltered and not associated with SARS-CoV-2 incidence. Demographics, disease durations, and molecular subtypes of sporadic CJD (sCJD) were largely consistent across periods, although a higher proportion of females were tested during COVID and the prevalence of sCJD MV1 declined post-COVID.

CJD prevalence and characteristics remained stable during COVID-19 despite increased EP-QuIC test submissions. These findings verify that CJD surveillance in Canada remained vigilant during the pandemic and highlight the value of EP-QuIC CSF testing for comprehensive CJD monitoring.