Learning Objectives for this Presentation:
By the end of the presentation participants will be able to understand the possible association between Guillain-Barré Syndrome (GBS) and Meningococcal Conjugate Vaccine (MCV4)

Background:
In May 2005, CDC recommended routine MCV4 vaccination of adolescents and college students and concerns of a possible association of Guillain-Barré Syndrome (GBS) following vaccination arose. GBS is a rare, serious disorder involving inflammatory demyelination of the peripheral nerves.

Objectives:
To estimate the potential risk of GBS after MCV4.

Methods:
Reports of GBS came to the Vaccine Adverse Event Reporting System (VAERS), a passive surveillance system that accepts reports of vaccine adverse events (AEs). The case definition used defined the onset interval to include days 0-42 days following vaccination. Reporting rate of GBS after MCV4 vaccination for persons aged 11-19 years, using manufacturer data for distributed doses was compared with GBS incidence estimated from both the Healthcare Cost and Utilization Project (HCUP) and the Vaccine Safety Datalink (VSD).

Results:
Since October 2005, 17 cases of GBS were reported in 11-19 year olds; the cases were significantly clustered at onset intervals of 9-15 days following vaccination (p=0.012). The rate of GBS after MCV4 was 0.20 per 100,000 person-months. The ratio of the VAERS reporting rate to the background incidence rate was 1.78 (95% CI=1.02, 2.85) and 1.77 (95% CI=0.96, 3.07) using HCUP and VSD, respectively. Assuming these ratios are accurate, the number of excess cases of GBS for every one million doses distributed to 11-19 year olds is approximately 1.25 (95% CI = 0.058-5.99).

Conclusions:
The data suggest a small increased risk of GBS after MCV4 vaccination; due to data limitations, results should be interpreted with caution. Larger studies are being planned. Because of the risk of meningococcal disease these data do not change CDC's recommendations for MCV4 use.