Manufacturer’s Inserts and efficacy statements:
Menactra– Efficacy was inferred from Menomune. From a study involving 72 children, Menomune demonstrates an efficacy of: (As measured by bacterial antibody)
Group A- 72%
Group C- 58%
Group Y- 90%
Group W-135- 82%
*If vaccinated before the age of 4 yrs, efficacy declines to less than 10% within 3 years.
*If vaccinated after the age of 4 yrs, efficacy declines to approximately 67% within 3 years.
The Journal of the American Medical Association published a study of the Effectiveness of a Mass Immunization Campaign Against Serogroup C Meningococcal Disease in Quebec in 2001, which came to the conclusion that:
Protection from serogroup C MCD was indicated in the first 2 years after vaccine administration (VE, 65%; 95% confidence interval [CI], 20%-84%), but not in the next 3 years (VE, 0%; 95% CI, -5% to 65%).
*VE- vaccine effectiveness
There was no evidence of protection in children younger than 2 years; all 8 MCD cases in this age group occurred in vaccinees.