Vaccine Safety

GBS and Menactra Meningococcal Vaccine

The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA), in partnership with state health departments, are investigating cases of Guillain-Barré syndrome (GBS) among adolescents who recently received tetravalent (A,C, Y, W135) meningococcal conjugate vaccine (Meningococcal Polysaccharide Diphtheria Toxoid Conjugate Vaccine, Menactra®, Sanofi Pasteur [MCV4]).

As of February 25, 2008, more than 15 million doses of Menactra have been distributed, and the Vaccine Adverse Event Reporting System (VAERS) has received 26 confirmed case reports of GBS within 6 weeks of receipt of MCV4 Menactra meningococcal vaccination. Twenty four people, 11 to 19 years of age, experienced symptoms within 6 weeks after receiving Menactra. Two other reports of GBS among people aged 20 years and older also have been confirmed. The symptom onset was 2 to 33 days after vaccination. The timing and onset of neurological symptoms are reasons to gather further information.

While this data suggests a small increased risk of GBS following Menactra immunization, there are a number of limitations in the data. The findings should be viewed with caution until they can be studied further and clarified. At this time, CDC is unable to determine if Menactra increases a risk of GBS in people who receive the vaccine. GBS is a rare illness, and the expected background population rates of GBS are not known precisely. An ongoing known risk for serious meningococcal disease exists. Therefore, CDC recommends a continuation of current vaccination strategies.

CDC recommends that adolescents and their caregivers be informed of this ongoing investigation as part of the consent process for vaccination with MCV4. The Meningococcal Vaccine Information Statement should be used.

Whether receipt of MCV4 vaccine might increase the risk for recurrence of GBS is unknown. People with a history of GBS who are not in a high-risk group for invasive meningococcal disease should not receive MCV4.

Additional Facts

Invasive meningococcal disease--

Occurs in three common clinical forms: meningitis (49% of cases), blood infections (33%), and pneumonia (9%); other forms account for the remainder (9%).
Can have an abrupt onset with a rapid course of disease.
Has a case fatality rate of 10% to 14%; 11% to 19% of survivors suffer serious sequalae including deafness, neurologic deficit, or limb loss.
Affects approximately 1 in 100,000 people annually in the United States.
In the United States, almost all cases are caused by Neisseria menigitidis bacteria serogroups B, C, and Y.

High-risk groups for invasive Meningococcal disease include--

College freshmen living in dormitories
Microbiologists who are routinely exposed to isolates of N. meningitidis
Military recruits
People who travel to reside in countries where N. meningitidis is hyperendemic or epidemic, particularly if contact with the local population is prolonged
People who have terminal complement component deficiencies
People who have anatomic or functional asplenia

Meningococcal Vaccines

Two vaccines licensed in the United States protect against invasive meningococcal disease: tetravalent (A,C, Y, W135) meningococcal conjugate vaccine (MCV4) and tetravalent (A,C,Y, W135) Meningococcal Polysaccharide Vaccine (MPS4). Differences between the vaccines can be reviewed at Prevention and Control of Meningococcal Disease: Recommendations of the Advisory Committee on Immunization Practice (ACIP).
Currently, no vaccine licensed in the United States protects against serogroup B.
Since February 2005, CDC's Advisory Committee on Immunization Practices (ACIP) has recommended routine vaccination of adolescents from 11 to 12 years of age with MCV4. ACIP also recommends vaccination before high school entry (at approximately age 15 years) as an effective strategy to reduce meningococcal disease incidence among adolescents and young adults.
ACIP recommends routine vaccination with meningococcal vaccine (MCV4 is preferred for persons aged 11 to 55 years, MPS4 acceptable) who are at high risk for meningococcal disease, and during meningococcal outbreaks caused by vaccine-preventable serogroups.
Approximately 15.5 million doses of MCV4 have been distributed nationally since March 2005 (Sanofi Pasteur, unpublished data, February 2008). Although the number of doses distributed is known, the exact number of vaccine doses administered is unknown.

Guillain-Barré Syndrome (GBS)

GBS is a serious neurological disorder involving inflammatory demyelination of peripheral nerves. It can occur spontaneously or after certain events such as infections.
Illness is typically characterized by the subacute onset of progressive, symmetrical weakness in the legs and arms, with loss of reflexes. Sensory abnormalities, involvement of cranial nerves, and paralysis of respiratory muscles also can occur. A small portion of patients die, and 20% of hospitalized patients can have prolonged disability.
Campylobacter jejuni, which causes bacterial gastroenteritis, is one identified participating factor for GBS.
The precise rate of GBS in adolescents is unknown. Data from the Vaccine Safety Datalink Project and the Health Care Utilization Project on GBS incidence persons aged 11 to 19 years indicate a background annual incidence of 1 to 2 cases per 100,000 persons per year.
This finding suggests that the rate of GBS among MCV4 recipients based on the number of cases reported within six weeks of administration of MCV4 is similar to what might have been expected to occur by chance alone. However, the timing of the onset of neurological symptoms (within 1.5 to 5 weeks of vaccination) is of concern.

FDA and CDC request that providers or others with knowledge of possible cases of GBS (or other clinically significant adverse events) occurring after vaccination with MCV4 or other vaccines report them to VAERS online or by telephone at 1-800-822-7967.

CDC further requests that health care providers report other cases of GBS (even those not associated with MCV4 or other vaccination) that occur aomong people aged 11 to 19 years to state health departments in accordance with state or local disease reporting guidelines.