Vaccines Reduce Number of Meningitis Infections, but for How Long?

From the WebMD Archives

Jan. 9, 2001 -- Bacterial meningitis, an often devastating infection resulting in inflammation of the spinal cord and the fluid surrounding the cord and the brain, can cause death, brain damage, hearing loss, severe learning disabilities, and many other potentially devastating conditions. Infants, adolescents, and young adults are most susceptible to infection.

But parents and others who care for children and teens will be relieved to hear that two recent studies have given a big shot in the arm to meningitis prevention efforts. Last week, the British government announced that an aggressive immunization program using a new vaccine against a particularly virulent form of bacterial meningitis, meningitis C, reduced the number of new meningitis cases in the U.K. by up to 90%. And now Canadian researchers report similar success with a mass immunization campaign (using an older form of the vaccine) in the province of Quebec in 1992-1993.

Unlike the new vaccine used in the U.K., however, the vaccine type still in use in both Canada and in the U.S. appears to protect children and teens for only a few years, and infants under 2 get almost no protection, say Phillipe De Wals, PhD, and colleagues in the Jan. 10 issue of the Journal of the American Medical Association.

"The vaccine seems to be highly effective in adults and children over 15 years of age, but not for a long period. The [effectiveness] seems to last for two years, and there is not much indication of any protection after two years. ... Actually, the vaccine is not at all effective in young children and is of low effectiveness in children between 2 and 14 years," says De Wals, a professor in the department of Community Health Sciences at the University of Sherbrooke in Quebec.

This is in marked contrast to the British experience: Meningitis C infection rates in the U.K. among infants and 15- to 17-year-olds plummeted by 90%. As reported by WebMD U.K., only six babies under the age of 1 in the U.K. contracted meningitis C in 2000, compared with 32 the year before.

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So if the new vaccine is so effective, why isn't it in use in North America? The reasons are complex, but parents and caregivers can rest assured that the currently available U.S. and Canadian vaccines can protect most young people during meningitis outbreaks, infectious disease experts agree.

And, De Wals tells WebMD, the vaccine in current use in the U.S. and Canada has been highly successful at reducing outbreaks of meningitis C among U.S. military recruits, in college students, and among people who are traveling in high-risk areas for short periods. The relatively short duration of protection compared with vaccines for other diseases, however, precludes the use of currently available meningitis vaccines for lifetime protection.

In North America, bacterial meningitis outbreaks make the news because they tend to occur in clusters where young people are in close contact with one another for extended periods of time, such as schools or summer camps. But in other parts of the world, meningitis is a cruel fact of daily life, says Nancy Rosenstein, MD, from the National Center for Infectious Diseases at the CDC.

"In Africa in 1996, there were 250,000 cases of meningococcal disease and 25,000 deaths, so while every case in the developed world is very important, we see nowhere near the magnitude of disease they see in the developing world," she tells WebMD. Meningococcus is a group of bacteria which is most often responsible for meningitis.

And even though the currently available U.S. and Canadian vaccines wear off after a few years, that's long enough to reduce the risk of infection during outbreaks of the disease, which tend to flare up and disappear just as quickly, experts say.

In addition, the type of vaccine used in the U.K., which includes a bacterial protein that helps the body to recognize and destroy the bacteria, should be available in the U.S. within the next two to four years, and it will then be available for consideration as part of the routine childhood vaccination schedule, Rosenstein tells WebMD.

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But she also says that it may be asking a lot of doctors and parents to add yet another vaccination to the already complicated routine childhood immunization schedule. However, several vaccine manufacturers are reportedly working on new meningitis vaccines that can be combined with existing vaccines to simplify dosing, Rosenstein says.

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