Acute Arterial Ischemic Stroke Following COVID-19 Vaccination: A Systematic Review and Meta-analysis.

BACKGROUND: Acute arterial-ischemic-stroke (AIS) has been reported as a rare adverse-event following COVID-19-vaccination with mRNA or viral-vector vaccines. However, data are sparse regarding the risk of post-vaccination AIS and its potential association with thrombotic-thrombocytopenia-syndrome (TTS). METHODS: A systematic review and meta-analysis of randomized-controlled clinical trials (RCTs), pharmacovigilance registries, registry-based studies, observational cohorts and case-series was performed with the aim to calculate: (1) the pooled proportion of patients presenting with AIS following COVID-19-vaccination; (2) the prevalence of AIS after mRNA and vector-based vaccination; (3) the proportion of TTS among post-vaccination AIS-cases. Patient characteristics were assessed as secondary outcomes. RESULTS: Two RCTs, three cohort and eleven registry-based studies comprising 17,481 AIS-cases among 782,989,363 COVID-19-vaccinations were included in the meta-analysis. The pooled proportion of AIS following exposure to any COVID-19-vaccine type was 4.7 cases per 100,000 vaccinations (95%CI:2.2-8.1; I2=99.9%). The pooled proportion of AIS following mRNA-vaccination (9.2 cases per 100,000 vaccinations; 95%CI: 2.5-19.3; I2=99.9%) did not differ compared to adenovirus-based-vaccination (2.9 cases per 100,000 vaccinations; 95%CI: 0.3-7.8; I2=99.9%). No differences regarding demographics were disclosed between patients with AIS following mRNA- or vector-based vaccination. The pooled proportion of TTS among post-vaccination AIS-cases was 3.1% (95%CI: 0.7-7.2%; I2=78.8%). CONCLUSIONS: The pooled proportion of AIS following COVID-19 vaccination is comparable to the prevalence of AIS in the general population and much lower than the AIS prevalence among SARS-CoV-2-infected patients. TTS is very uncommonly reported in patients with AIS following COVID-19 vaccination.

Cerebral Venous Sinus Thrombosis and Thrombotic Events After Vector-Based COVID-19 Vaccines: A Systematic Review and Meta-analysis.

BACKGROUND AND OBJECTIVES: There is accumulating evidence supporting an association between the thrombosis and thrombocytopenia syndrome (TTS) and adenovirus vector-based vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Yet TTS and TTS-associated cerebral venous sinus thrombosis (CVST) remain poorly characterized. We aim to systematically evaluate the proportion of CVST among TTS cases and assess its characteristics and outcomes. METHODS: We performed a systematic review and meta-analysis of clinical trials, cohorts, case series, and registry-based studies with the aim to assess (1) the pooled mortality rate of CVST, TTS-associated CVST, and TTS and (2) the pooled proportion of patients with CVST among patients with any thrombotic event and TTS. Secondary outcomes comprised clinical characteristics of patients with postvaccination thrombotic event. This meta-analysis is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was written according to the Meta-analysis of Observational Studies in Epidemiology proposal. RESULTS: Sixty-nine studies were included in the qualitative analysis comprising 370 patients with CVST out of 4,182 patients with any thrombotic event associated with SARS-CoV-2 vector-based vaccine administration. Twenty-three studies were included further in quantitative meta-analysis. Among TTS cases, the pooled proportion of CVST was 51% (95% confidence interval [CI] 36%-66%; I 2 = 61%). TTS was independently associated with a higher likelihood of CVST when compared to patients without TTS with thrombotic events after vaccination (odds ratio 13.8; 95% CI 2.0-97.3; I 2 = 78%). The pooled mortality rates of TTS and TTS-associated CVST were 28% (95% CI 21%-36%) and 38% (95% CI 27%-49%), respectively. Thrombotic complications developed within 2 weeks of exposure to vector-based SARS-CoV-2 vaccines (mean interval 10 days; 95% CI 8-12) and affected predominantly women (69%; 95% CI 60%-77%) under age 45, even in the absence of prothrombotic risk factors. DISCUSSION: Approximately half of patients with TTS present with CVST; almost one-third of patients with TTS do not survive. Further research is required to identify independent predictors of TTS following adenovirus vector-based vaccination. REGISTRATION INFORMATION: The prespecified study protocol has been registered in the International Prospective Register of Ongoing Systematic Reviews PROSPERO (CRD42021250709).

Prevalence, clinical characteristics and outcomes of Guillain-Barré syndrome spectrum associated with COVID-19: A systematic review and meta-analysis.

BACKGROUND AND PURPOSE: Mounting evidence supports an association between Guillain-Barré syndrome spectrum (GBSs) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, GBSs in the setting of coronavirus disease 2019 (COVID-19) remains poorly characterized, whilst GBSs prevalence amongst COVID-19 patients has not been previously systematically evaluated using a meta-analytical approach. METHODS: A systematic review and meta-analysis of observational cohort and case series studies reporting on the occurrence, clinical characteristics and outcomes of patients with COVID-19-associated GBSs was performed. A random-effects model was used to calculate pooled estimates and odds ratios (ORs) with corresponding 95% confidence intervals (CIs), compared to non-COVID-19, contemporary or historical GBSs patients. RESULTS: Eighteen eligible studies (11 cohorts, seven case series) were identified including a total of 136,746 COVID-19 patients. Amongst COVID-19 patients, including hospitalized and non-hospitalized cases, the pooled GBSs prevalence was 0.15‰ (95% CI 0%-0.49‰; I2  = 96%). Compared with non-infected contemporary or historical controls, patients with SARS-CoV-2 infection had increased odds for demyelinating GBSs subtypes (OR 3.27, 95% CI 1.32%-8.09%; I2  = 0%). In SARS-CoV-2-infected patients, olfactory or concomitant cranial nerve involvement was noted in 41.4% (95% CI 3.5%-60.4%; I2  = 46%) and 42.8% (95% CI 32.8%-53%; I2  = 0%) of the patients, respectively. Clinical outcomes including in-hospital mortality were comparable between COVID-19 GBSs patients and non-infected contemporary or historical GBSs controls. CONCLUSION: GBSs prevalence was estimated at 15 cases per 100,000 SARS-CoV-2 infections. COVID-19 appears to be associated with an increased likelihood of GBSs and with demyelinating GBSs variants in particular.