CITF-funded findings on Post-COVID Conditions

It is now estimated that nearly 1 in 10 people who have a SARS-CoV-2 infection (hospitalized and non-hospitalized individuals) may develop Long COVID, which amounts to a global burden of over 16 million people. While the underlying cause of Long COVID remains largely unknown, it is evident that this condition can affect individuals of all ages and is not predicated on how severe the initial COVID-19 case was. Here, we summarize results from the five presentations given during the breakout session “Post-COVID Conditions” at the CITF Scientific Meeting in Vancouver, March 8-10, 2023. The study teams presented findings on the prevalence of Post-COVID Conditions in Canada, Long COVID patient characteristics, and the impact of vaccination after Long COVID.

1. Presenter and CITF PI Dr. Manali Mukherjee: Autoimmunity in post-acute COVID-19 sequelae (PACS): An update on rheumatological findings

This study sought to determine if specific autoantibodies that persist over one year in some individuals were associated with the persistence of symptoms and diagnosis of post-acute COVID-19 sequelae (PACS) or Long COVID.

• 80% of individuals who recovered from COVID-19 (irrespective of Long COVID diagnosis) had anti-nuclear antibody (ANA) positivity of two or more at three to six months, with a significant attenuation at one year.
• Anti-U1-snRNP, anti-SS-B/La, and anti-PM-Scl (autoantibodies with confirmed pathogenicity in systemic autoimmune diseases) were observed at one year and were found to be present in about 30% of individuals who had recovered from COVID-19.
• At one year post COVID, the presence of U1-snRNP and SS-B/La were predictors of fatigue and dyspnea (shortness of breath) in post-COVID patients.
• Pro-inflammatory cytokines, in particular TNF𝛼, were associated with common Long COVID symptoms, particularly fatigue at one year.

2. Presenter and CITF PI Dr. Emilia Liana Falcone: Vaccination after developing Long COVID is associated with reduced clinical symptoms and certain inflammatory markers but does not alter levels of persistent SARS-CoV-2 antigens

This study aimed to determine whether COVID-19 vaccination in patients with PCC impacted the evolution of Long COVID symptoms, their psychological well-being, and their markers of systemic inflammation, as well as the persistence of viral antigens and humoral immune responses.

• One or two COVID-19 vaccine dose(s) was shown to decrease the number of PCC symptoms and the number of affected organs. One or two doses also increased the WHO-5 Well-Being score.
• Vaccinated individuals had decreased markers of systemic inflammation including interleukin-1ß and stem cell factor (SCF).

3. Presenter Mr. Jeffrey Hau and CITF PI Dr. Corinne Hohl: Patient characteristics and prevalence of the Post COVID-19 Condition in Canada using the World Health Organization definition: A CCEDRRN patient-oriented cohort study

This study sought to determine characteristics of emergency department (ED) patients with and without Post COVID-19 Condition (PCC), three, six, and 12 months after having COVID-19, and the prevalence of PCC among ED patients who tested positive with COVID-19.

• There was higher reported risk of PCC in Canadian ED patients compared to previous Canadian reports, with the mean age of PCC positive patients being 52 years old.
• Among PCC positive patients, 78.6% had not received a COVID-19 vaccine, 56% were white, and 30.9% had no comorbidities. Among those with comorbidities, 27.3% had hypertension and 16.3% had diabetes.
• Since the start of follow-ups of ED patients with COVID-19 in November 2021, there was a high prevalence of PCC at 3 (39.6%), 6 (38.8%), and 12 months (34.1%).

4. Presenter Dr. Michael Asamoah-Boaheng and CITF PI Dr. Brian Grunau: The association of post-COVID-related symptoms and preceding SARS-CoV-2 infection among fully vaccinated paramedics in Canada

This study investigated the relationship between post-COVID-19 related (Long COVID) symptoms and preceding SARS-CoV-2 infection among fully vaccinated paramedics in Canada.

• The number of post-COVID-related symptoms was not affected by whether the person knew they had had COVID-19 or not.
• Paramedics who had been infected with SARS-CoV-2 did not take more medical leave than those who had not.
• To reduce the incidence and impact of Long COVID, COVID-19 prevention strategies should be implemented and there should be routine assessments for those who previously had COVID-19.

5. Presenter Dr. Jeff Latimer and CITF PI Dr. Ron Gravel: The Canadian COVID-19 Antibody and Health Survey: Deriving national SARS CoV-2 seroprevalence and symptomology estimates from self-collected biospecimens and questionnaire data

The Canadian COVID-19 Antibody and Health Survey (CCAHS) aimed to: estimate the prevalence of Post-COVID-19 Conditions (PCC) (also known as Long COVID) and assess both the antibody/immunity profiles and acute infection status of Canadians. The study served to test the feasibility of deploying a wide-scale survey-based methodology that included self-administered biospecimen tests to estimate the national seroprevalence of SARS-CoV-2 infections.

• 35% of Canadian adults whose saliva test showed they had a current or recent infection did not know or suspect they had the virus (they were unaware of their infection) at the time of the saliva test.
• 4% of Canadian adults whose saliva test showed detectable amounts of the virus reported that they had tested positive for COVID-19 more than three months earlier, indicating potential reinfection.
• 8% of Canadian adults who had – or thought they had – COVID-19 still experienced symptoms three or more months after infection. The most common unresolved symptoms included fatigue (72%), cough (40%), shortness of breath (39%), and brain fog (33%).
• Risk factors for developing post-COVID-19 condition included being female, having a pre-existing chronic condition, having a body mass index greater than 35 kg/m², having been infected with SARS-CoV-2 before July 2021, and/or having increased severity of symptoms at the time of infection.