The MHRA are analysing all reports of GBS following COVID-19 vaccination and this information will be shared when it becomes available. A causal link between COVID-19 vaccination and GBS has not been proven for the Pfizer/BioNTech and Moderna vaccines and cases of GBS that occur following vaccination may occur by chance, with a background rate of GBS of 2 per 100,000 per year. For the AZ vaccine, GBS has very rarely been reported within 6 weeks of the first dose, with the risk approximately 5.6 extra cases of GBS per million doses. Rates after the second dose are within background levels and there is no evidence of a higher rate of reporting in individuals who have had GBS previously. See the Green Book for further information. For the Johnson & Johnson (Janssen) vaccine which has a 1 dose schedule, data from the US indicates that there is an increased risk of GBS in the 42 days following this single dose, and investigations are ongoing to assess whether there is a causal relationship between the vaccine and the cases of GBS.