DEAR DR. ROACH: Why aren’t meningococcal vaccines recommended for people over the age of 23? Are they assuming (wrongly) that most people have already received them or that most won’t (again, probably wrongly) be exposed?

When I worked in the emergency room long ago before there was a vaccine, we had two patients in a row die from meningococcal meningitis, and the entire staff that was on duty when they were brought in had to be treated prophylactically. Meningococcal meningitis terrifies me, and I was never vaccinated for it. According to the recommendations, I was already way over the age range when the vaccine came out.

— H.R.

ANSWER: Meningococcus (Neisseria meningitidis) is, indeed, a terrifying bacteria. Like you, I have seen people die within hours of its presentation. Even people who survive it may have long-term complications. I can understand wondering why there isn’t a recommendation to vaccinate everyone against this disease.

A recommendation for a preventive maneuver such as a vaccination is made when the benefit is greater than the risk — and when the cost of intervention is worth what society is willing to pay. In the case of the meningococcal vaccine, the vaccine is highly safe and effective. But because the disease is rare, it is only cost-effective when used in people who are at a high risk, either due to an increased likelihood of exposure or because of an increased risk of disease due to immune deficiency.

The vaccines (there are two separate vaccines; one for serogroups ACWY and another for serogroup B) are recommended for adolescents and young adults, especially when they are going to be living close together such as in a college dormitory, where there is a high risk of exposure.

Ideally, the first dose of MenACWY is given between ages 11-12, with a booster dose within five years of college entry.

The MenB vaccine is given in two doses six months apart between ages 16-18. MenACWY is recommended for all, while the recommendations for MenB are being discussed.

Because of the low prevalence of the disease (partially related to the success of the vaccine) and the high cost of the vaccine, it is not recommended for healthy adults.

Dr. Roach cannot respond personally to all letters. But he will publish his answers in this daily column. Send your questions to ToYourGoodHealth@med.cornell.edu.

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