Guillain Barre syndrome; Fisher syndrome; Limb weakness; This case was reported in a literature article and described the occurrence of guillain barre syndrome in a elderly patient who received Flu unspecified (Flu vaccine) for prophylaxis.   On an unknown date, the patient received Flu vaccine at an unknown dose. On an unknown date, less than 2 months after receiving Flu vaccine, the patient experienced guillain barre syndrome (serious criteria hospitalization and GSK medically significant), fisher syndrome (serious criteria hospitalization and GSK medically significant) and weakness of limbs. On an unknown date, the outcome of the guillain barre syndrome, fisher syndrome and weakness of limbs were unknown.   The reporter considered the guillain barre syndrome, fisher syndrome and weakness of limbs to be related to Flu vaccine.  Additional details were provided as follows: This case was reported in a literature article and described the occurrence of guillain-barre syndrome (GBS) and fisher syndrome (FS) in a patient aged more or equal to 65-year-old of unspecified gender who was vaccinated with unspecified 2015-2016 seasonal of influenza vaccine (manufacturer unknown) for prophylaxis. This case corresponds to result section reported in this literature article The patient was the part of the near real-time surveillance for GBS claims after influenza vaccination of insurance fee-for-service (FFS) beneficiaries using the updating sequential probability ratio test throughout the influenza seasons and SCRI analyses at the end of the 2015-2016 and 2016-2017 seasons. The aimed of this study was to evaluate this signal by conducting chart reviews in the 2015-2016 season followed by self-controlled risk interval (SCRI) analyses of chart-confirmed and imputed cases. [In this study, for the 2015-2016 season SCRI analysis, they used chart-confirmed GBS cases. In 2016-2017 season they conducted SCRI analyses of the claims-based GBS cases and attributed GBS cases (based on the positive predictive value (PPV) of the GBS diagnoses obtained by chart reviews in the previous season). Of the 95 chart-confirmed GBS cases, they noted a history of antecedent respiratory or gastrointestinal illness within six weeks prior to onset of GBS symptoms in 47 charts, one of which had a documented history of Campylobacter jejuni. They identified claims for influenza vaccines and vaccines administered concomitantly (pneumococcal, hepatitis B, and tetanus toxoid-containing vaccines) using Healthcare Common Procedure Coding System (HCPCS) and Current Procedural Terminology (CPT) codes. They conducted influenza infection adjustment using high" and low" influenza weeks, which were assigned as such using weekly oseltamivir prescription rates as well as use rates of rapid influenza tests (RIT) followed by an oseltamivir prescription within the subsequent two days]. On unspecified date, the patient had received unspecified 2015-2016 seasonal influenza vaccine (administration route and site unspecified, dosage unknown; batch number not provided). The age of vaccination was not provided. [In this study, the vaccine type (high dose (HD) and standard dose (SD)), and presence of concomitant vaccination. The only HD vaccine administered in both seasons was the inactivated trivalent high dose vaccine (60 mg hemagglutinin per strain). The SD group included inactivated trivalent and quadrivalent (15 mg hemagglutinin per strain) vaccines A total of 13,366,005 insurance FFS influenza-vaccinated beneficiaries were observed for our SCRI analyses. Of these, 6,936,021 received the HD vaccine, 6,218,036 received the SD vaccines, and the remaining received other influenza vaccines (recombinant, intradermal, and cell-culture based) or only had general influenza vaccine codes but no specific codes for a vaccine type.]. On unspecified date between 2015 and 2016, in between the 1 and 42 days risk window, the patient had diagnosed with the guillain-barre syndrome (GBS) and fisher syndrome (FS) as per the Brighton case definition. [In this study, the primary and secondary risk windows were 1-42 and 8-21 days post-vaccination respectively. They defined exposure as a beneficiary's first influenza vaccination during the season, and outcome as the first occurrence of GBS in the inpatient setting during the post-vaccination window of interest. They used Brighton Collaboration's case definitions for GBS and Fisher Syndrome (FS), a variant of GBS, to classify these cases and considered cases classified as Brighton Level 1, 2, or 3 as chart-confirmed" GBS cases. For the 2015-2016 season, our claims-based near real-time surveillance using the Updating Sequential Probability Ratio Test (USPRT) first revealed a GBS signal in week 16 of surveillance (as of 29th November 2015) among HD vaccines aged more or equal than 65 years as a risk of GBS in the 0 to 42 day window and as a risk of GBS in the 7 to 21 day window. Of note, in the 2015-2016 season, the 0 to 42 day and 7 to 21 day risk windows were used for near real-time surveillance; however, they changed the risk windows to 1 to 42 and 8 to 21 days post-vaccination for the SCRI analyses and near real-time surveillance for subsequent seasons to better align with the existing literature. In the subsequent weeks they observed a GBS signal in week 26 (as of February 2, 2016) for all beneficiaries vaccinated with all seasonal vaccines as a risk of GBS cases in the 0 to 42 day window. The demographic characteristics of the influenza-vaccinated beneficiaries and the GBS cases in the 2 risk windows. They obtained 133 charts. They found 158 claims-based GBS cases in the 84 days post-vaccination that met our study criteria. All cases except one were identified with the ICD-10 code. Three cases were observed after the January 22, 2016 cut-off, and they requested medical charts for the remaining 155 cases. They obtained 133charts. Of these, they confirmed 95 by chart review as GBS cases. Our analysis showed a PPV of an inpatient diagnosis of GBS in ICD-10. By chart abstraction they found that seven cases identified as GBS by claims had FS noted in the charts. However, none of these seven cases met the criteria for FS and four did not meet the criteria for GBS. Of the remaining three cases, they excluded one due to the subject being noted as less than 65 years of age. They included the remaining two cases in the SCRI analysis. Both cases occurred in the 1 to 42 day risk window; one also occurred in the 8 to 21 day window. Even though these two remaining cases were diagnosed by the physicians as FS, they both had limb weakness in addition to FS features and were thus classified as GBS.].  This case has been considered as serious due to the hospitalization. Treatment was unknown. The outcome of the event was not provided. The authors commented, "Our SCRI results did not show an excess GBS risk in the 1-42 day risk window either in the overall analysis or in any of the sub-analyses by vaccine type. For the secondary 8-21 day risk window, we found a statistically significant increased GBS for all seasonal vaccines. Our chart-confirmed analysis showed that the attributable risk in the secondary (8-21 day) risk window for all seasonal vaccines was slightly less than one excess GBS case per million vaccines, and that for the HD vaccine was slightly less than two excess cases of GBS per million vaccines. These findings are consistent with the risks noted on the package insert of influenza vaccines distributed in specific country. Our secondary analysis finding of a higher GBS risk among males and individuals aged more or equal to 75 years who received seasonal vaccines is consistent with existing literature. We considered the possibility that the difference may be related to egg-based versus recombinant influenza vaccine, which was included in our SD vaccine group". The author concluded, "we did not find an excess GBS risk in our primary analysis. The excess risk in some of our secondary analyses was close to what was expected; however, the slightly elevated GBS risk after all seasonal and HD vaccines, but not after standard dose vaccines is hypothesis-generating. This difference between HD and SD vaccines may be related to vaccine factors such as the amount of antigen or the antigen strains in various seasons or related to host factors. The risk of GBS after influenza disease is estimated to be much greater than the potential risk following influenza vaccine, ranging from four to almost 16 times higher, and the benefits of influenza vaccines in preventing morbidity and mortality heavily outweigh this risk. Influenza vaccines continue to be our best defense against influenza disease and the morbidity and mortality associated with it." This is 1 of the 4 valid cases reported in this literature article.