Herd immunity may expand benefit of vaccination
A British study compared attack rates for meningococcal C disease in children from infancy to age 18 before and 1 to 2 years after the institution of a nationwide meningococcal serogroup C conjugate vaccination. Vaccine coverage ranged from 66% (adolescents) to 87% (schoolchildren), and vaccine efficacy was 94% to 96%. Incidence of meningococcal C disease in the unvaccinated children also decreased by 52% to 67% (from 4.08/100,000 to 1.36/100,000).5
Vaccinating adolescents may be particularly helpful for building herd immunity. A Norwegian study of nasopharyngeal meningococcal carriage among 943 unimmunized individuals ages 2 months to 95 years found a carriage rate of 28% among 15- to 24-year-olds, compared with 9.6% overall.6
High hospitalization rates in US military recruits during 1964 to 1970 (25.2/100,000) led to the development of the meningococcal polysaccharide vaccine. Since 1971, all new military recruits have received polysaccharide meningococcal vaccine, and for the period 1990 to 1998 the hospitalization rate for meningococcal disease among active duty service members had decreased by 98% (to 0.51/100,000).7
Recommendations from others
The Advisory Committee on Immunization Practices,2 American Academy of Pediatrics,8 American Academy of Family Physicians,9 and American College Association10 recommendations are summarized in the TABLE. Recommendations for vaccination during meningococcal disease outbreaks can be found at www.cdc.gov.2
TABLE
Who should get vaccinated—and when
| TARGET POPULATION | VACCINE TYPE |
|---|---|
| Children 2–10 years at increased risk* | MPSV4† |
| Adolescents 11–12 years | MCV4 |
| Adolescents at high school entry or 15 years of age without prior vaccination | MCV4 |
| College freshmen planning to reside in dormitories | MCV4‡ |
| Patients ages 11–55 at increased risk* | MCV4‡ |
| Patients older than 55 years at increased risk* | MPSV4 |
| Microbiologist, lab personnel exposed to N meningitides | MCV4‡ |
| Military recruits | MCV4‡ |
| *“Increased risk” is defined by terminal complement deficiency, anatomic or functional asplenia, travel to endemic areas, HIV infection (optional). | |
| †May be repeated every 3 to 5 years if increased risk continues. | |
| ‡MPSV4 is an acceptable alternative. | |
| MPSV4, meningococcal polysaccharide vaccine; MCV4, meningococcal polysaccharide diphtheria toxoid conjugate vaccine. | |
| Adapted from Harrison, Clinical Microbiology Reviews 2006;1 Kimmel, Am Fam Physician 2005.9 | |