Pandemic influenza A vaccination and incidence of Guillain-Barre syndrome in Korea

Background: Many studies have investigated the association between Guillain-Barre syndrome (GBS) and vaccinations during the influenza A H1N1 pandemic of 2009 (pH1N1). Based on a nationally representative sample, we estimated the incidence of GBS during the pandemic period in Korea. Materials and methods: All medical records of CBS cases were reviewed in 28 randomly selected hospitals during 2008-2010, and the number of CBS cases at the national level was extrapolated using emergency care utilization data. The CBS rate per 100,000 person-years was estimated in the reference and pandemic periods. Results: The incidence of CBS was 0.63 (95% CI: 0.37-0.89) per 100,000 person-years in the reference period and 0.87(0.49-1.26) in the pandemic period. During the vaccination season, the pandemic period CBS incidence rate was not significantly higher than the reference period incidence rate (rate ratio: 1.52; 0.99-2.32), but difference was observed among persons aged 20-34 years. Rate of CBS increased after pH1N1 vaccination compared to the reference period (1.46,1.26-1.68). Discussion: The incidence of CBS increased slightly but not significantly during the pandemic period, although pH1N1 vaccination increased the CBS rate. Therefore,, mass influenza vaccination programs should not be precluded on the basis of CBS. (C) 2015 Elsevier Ltd. All rights reserved.