An advisory panel to the Centers for Disease Control and Prevention voted on October 27 to recommend a meningitis booster shot for 16-year olds.

The vote was in response to information that the vaccine, originally thought to be protective for 10 years, begins to lose effectiveness within five years. There are no other known problems with the vaccine, which was first introduced in 2005.

Others favored simply raising the recommended vaccination age to 14 or 15, but in the end, six panelists felt uneasy about leaving the 11-14 age group unprotected.

The vaccine, called MSV4, is recommended for all children aged 11-12. It protects against meningitis caused by the bacterium Neisseria meningitidis, also known as meningococcus.

Meningitis is a potentially fatal disease where the membranes surrounding the brain and spinal cord become infected. Meningitis can be caused by several different bacteria, viruses or other microorganisms. Bacterial meningitis is usually the most serious.

Children commonly receive two different types of meningitis vaccine by the age of 2. But these vaccines do not protect against meningococcus.

The incidence of meningitis tends to rise between the ages of 11 and 19. The MSV4 vaccine was originally recommended for college freshmen because of a high meningitis rate among college students living in dormitories. In 2007, it was recommended that the vaccine be given to all 11-12 year olds with the thought that the vaccine would remain protective for 10 years.

The new recommendation was approved by a 6-5 vote, with three members abstaining.

As reported by Reuters, the closeness of the vote was because there has been a large decline in meningitis cases in the last decade. Some panelists questioned whether any action was necessary. Others favored simply raising the recommended vaccination age to 14 or 15, but in the end, six panelists felt uneasy about leaving the 11-14 age group unprotected.

The Advisory Committee on Immunization Practices periodically issues recommendations to the CDC. Although the CDC is not bound by these recommendations, it usually adopts them.

The committee also recommended that people 65 and older who spend time with infants get vaccinated against whooping cough, as a measure to protect infants too young to be vaccinated themselves. This is in response to an outbreak of whooping cough in California, where more than 6,200 cases have been reported so far in 2010.

There are seven commonly available vaccines that protect against meningitis. They protect against three different meningitis-causing bacteria and each vaccine is recommended for a specific age group. Detailed information about these vaccines can be found at the CDC website. These vaccines are listed under the headings Hib, meningococcal, PCV and PPSV.