New-onset anesthesia/paresthesia following the administration of COVID-19 vaccines in Quebec, Canada.

Background: In Canada, anesthesia/paresthesia were the most frequently reported adverse events following immunization (AEFI) against SARS-CoV-2. This study aims to describe the frequency and characteristics of anesthesia/paresthesia cases temporally associated with a first or second dose of COVID-19 vaccines administered in Quebec, Canada.

Methods: Cases were extracted among AEFI reports submitted to the passive surveillance system. Sociodemographic, vaccination and AEFI information were obtained from the immunization registry. Signs, symptoms and anatomical location were manually extracted from clinical narratives.

Results: From December 13, 2020 to December 31, 2022, 15.2 million doses of vaccines were administered in Quebec. By July 1, 2022, 1024 cases of anesthesia/paresthesia following COVID-19 vaccination had been reported. The global reporting rate was 7.7 per 100,000 doses administered. Rates were higher with the first than the second dose (11.4 vs. 3.8 per 100,000 doses), and higher with ChAdOx1 than with mRNA vaccines Comirnaty™ (BNT-162b2, Pfizer BioNTech) or Spikevax™ (mRNA-1273, Moderna) (28.7 vs. 6.1 and 7.9, respectively). Rates were 3- to 4-times higher in women, with the highest rate ratios among those 18-49 years of age. Median time to onset was 24 h (IQR: 3-96). Paresthesia, hypoesthesia/anesthesia (83 %) were more common than dysesthesias (13 %). Symptoms were reported mostly in upper limbs (62 %), but also frequently in lower limbs (47 %) or the face (42 %). Most reported mild (41 %) or moderate (48 %) symptoms, with a median duration of 5 days (IQR: 2-15), although symptoms lasting 1-5 months (12 %) or over 6 months (1 %) were also reported.

Conclusions: Symptoms of anesthesia/paresthesia are commonly reported following the administration of several vaccines, including those against COVID-19. In most instances, symptoms occur shortly after vaccination, have a limited impact on daily activities, and resolve spontaneously within a month of onset. A small proportion of cases report sensory and/or motor symptom of longer duration, which remain undiagnosed following neurological investigations. Despite being a common occurrence, post-vaccination sensory disturbances remain a poorly understood phenomenon that warrants further study.