In those who have received intravenous immunoglobulins, a smaller increase in IgG in the blood two weeks after administration is associated with poorer mobility outcomes at six months than those whose IgG level increased substantially. If the disease continues to progress beyond four weeks, or there are multiple fluctuations in the severity (more than two in eight weeks), the diagnosis may be chronic inflammatory demyelinating polyneuropathy, which is treated differently.In research studies, the outcome from an episode of Guillain–Barré syndrome is recorded on a scale from 0 to 6, where 0 denotes completely healthy; 1 very minor symptoms but able to run; 2 able to walk but not to run; 3 requiring a stick or other support; 4 confined to bed or chair; 5 requiring long-term respiratory support; 6 death.The health-related quality of life (HRQL) after an attack of Guillain–Barré syndrome can be significantly impaired. About a fifth are unable to walk unaided after six months, and many experience chronic pain, fatigue and difficulty with work, education, hobbies and social activities. HRQL improves significantly in the first year. Epidemiology
In Western countries, the number of new episodes per year has been estimated to be between 0.89 and 1.89 cases per 100,000 people. Children and young adults are less likely to be affected than the elderly: the relative risk increases by 20% for every decade of life. Men are more likely to develop Guillain–Barré syndrome than women; the relative risk for men is 1.78 compared to women.The distribution of subtypes varies between countries.
Natural influenza infection is a stronger risk factor for the development of GBS than is influenza vaccination and the vaccination reduced the risk of GBS overall by lowering the risk of catching influenza.In the United States, GBS after seasonal influenza vaccination is listed on the federal governments vaccine injury table. On March 24, 2021, after reviewing several post-marketing observational studies, where an increased risk of Guillain–Barré syndrome was observed after 42 days following vaccination with the Zoster vaccine Shingrix, the FDA required safety label changes from the manufacturer GlaxoSmithKline to include warnings for risk of Guillain–Barré syndrome. COVID-19 infection or vaccine related
GBS has been reported in association with COVID-19, and may be a potential neurological complication of the disease. GBS has been reported as a very rare side effect of the Janssen and the Oxford–AstraZeneca COVID-19 vaccine for COVID-19 and European Medicines Agency (EMA) had issued warning to the patients and healthcare providers. The incidence of GBS following the vaccination with the Oxford-AstraZeneca vaccine was originally reported as being lower than the incidence of GBS following a COVID-19 infection. More recent studies, however, found no measurable link between COVID-19 infection and GBS, while correlations with a first dose of AstraZeneca or Janssen vaccines were still positive.COVID-19 has been reported as causing peripheral neuropathy and more recently some evidence of aggravation of autoimmune disorders including GBS. Some studies are now finding Parkinsons Disease is more common in infection survivors.