Eurosurveillance - Volume 28, Issue 24, 15 June 2023

Guillain-Barré syndrome (GBS) has been associated with vaccination against COVID-19.

We aimed to compare clinical characteristics and analyse excess GBS cases following administration of different COVID-19 and influenza vaccines in Germany versus the expected numbers estimated from pre-pandemic background incidence rates.

We analysed safety surveillance data reported to the German national competent authority between 27 December 2020 and 31 August 2021. GBS cases were validated according to Brighton Collaboration (BC) criteria. We conducted observed vs expected (OvE) analyses on cases fulfilling BC criteria levels 1 to 4 for all four European Medicines Agency-approved COVID-19 vaccines and for influenza vaccines.

A total of 214 GBS cases after COVID-19 vaccination had been reported, of whom 156 were eligible for further analysis. Standardised morbidity ratio estimates 3–42 days after vaccination were 0.34 (95% confidence interval (CI): 0.25–0.44) for Comirnaty, 0.38 (95% CI: 0.15–0.79) for Spikevax, 3.10 (95% CI: 2.44–3.88) for Vaxzevria, 4.16 (95% CI: 2.64–6.24) for COVID-19 Vaccine Janssen and 0.60 (95% CI: 0.35–0.94) for influenza vaccines. Bilateral facial paresis was reported in 19.7% and 26.1% of the 156 GBS cases following vaccination with Vaxzevria and COVID-19 Vaccine Janssen, respectively, and only in 6% of cases exposed to Comirnaty.

Three and four times more GBS cases than expected were reported after vaccination with Vaxzevria and COVID-19 Vaccine Janssen, respectively, therefore GBS might be an adverse event of vector-based vaccines. Bifacial paresis was more common in cases with GBS following vaccination with vector-based than mRNA COVID-19 vaccines.

Appropriate vaccination strategies have been key to controlling the outbreak of mpox outside endemic areas in 2022, yet few studies have provided information on mpox vaccine effectiveness (VE).

To assess VE after one dose of a third-generation smallpox vaccine against mpox when given as post-exposure prophylaxis (PEP) within 14 days.

A survival analysis in a prospective cohort of close contacts of laboratory-confirmed mpox cases was conducted from the beginning of the outbreak in the region of Madrid in May 2022. The study included contacts of cases in this region diagnosed between 17 May and 15 August 2022. Follow up was up to 49 days. A multivariate proportional hazard model was used to evaluate VE in the presence of confounding and interaction.

Information was obtained from 484 close contacts, of which 230 were vaccinated within 14 days of exposure. Of the close contacts, 57 became ill during follow-up, eight vaccinated and 49 unvaccinated. The adjusted effectiveness of the vaccine was 88.8% (95% CI: 76.0–94.7). Among sexual contacts, VE was 93.6% (95% CI: 72.1–98.5) for non-cohabitants and 88.6% (95% CI: 66.1–96.2) for cohabitants.

Post-exposure prophylaxis of close contacts of mpox cases is an effective measure that can contribute to reducing the number of cases and eventually the symptoms of breakthrough infections. The continued use of PEP together with pre-exposure prophylaxis by vaccination and other population-targeted prevention measures are key factors in controlling an mpox outbreak.