Beidari et al. (2026)
- Authors: Malika Seydou Beidari, Martyne Audet, Stéphane Turcotte, Raoul Daoust, Patrick Archambault, Simon Decary, Richard Fleet, Alexis Cournoyer, Judith Fafard, Eric Mercier
- Institutes: Centre de recherche du CHU de Québec-Université Laval, Québec, QC, Canada, Centre de recherche intégrée pour un système de santé apprenant en santé et services sociaux, Lévis, QC, Canada, Département de médecine de famille et de médecine d’urgence, Université de Montréal, Montréal, QC, Canada
- Publisher: medRxiv
- Link: DOI
Summary
This study identifies specific risk factors that may predict a worsening of Long COVID symptoms following vaccination. While most patients do not experience a decline, identifying those at higher risk—such as those receiving the Moderna vaccine or having a history of persistent cough—allows for more personalized medical guidance. These findings contribute to the ongoing discussion regarding the immunological interaction between vaccines and existing Post-COVID-19 Condition (PCC).
What was researched?
The study investigated which factors are associated with the deterioration of Post-COVID-19 Condition (PCC) symptoms in patients who received a SARS-CoV-2 vaccine dose at least 90 days after their initial infection.
Why was it researched?
While vaccination generally helps prevent severe disease, some patients with Long COVID report a worsening of their symptoms after immunization. Researchers sought to identify clinical or demographic characteristics that could explain this phenomenon.
How was it researched?
This multicenter cohort study analyzed 476 patients from 33 Canadian emergency departments who met the WHO definition for PCC. Data were collected through telephone questionnaires, and researchers used logistic regression models to identify significant associations between patient factors and symptom changes.
What has been found?
The study found that 28.8% of participants reported a deterioration in their symptoms after vaccination. Two factors were significantly linked to this decline: receiving the Moderna (mRNA-1273) 💊 vaccine and having a persistent cough three months after the initial infection. No significant associations were found for age or sex.
Discussion
The results suggest that the type of vaccine and specific initial symptoms might influence the post-vaccination course for PCC patients. Limitations include the reliance on self-reported data and the lack of a control group not receiving a vaccine.
Conclusion & Future Work
Post-infection vaccination may increase the risk of symptom deterioration in specific PCC subgroups. Future research should focus on the underlying immunological mechanisms and tailoring vaccination strategies for patients already suffering from Long COVID.