Some people experience hearing
loss following meningitis, but it may have been the other
way around for five-year-old Kelly Greene. Kelly, who's
been deaf since birth, received a cochlear implant as
a baby. Since infants who receive cochlear implants are
much more susceptible to meningitis, Kelly was given the
traditional precautionary vaccine. Unfortunately, she
got the disease anyway. As it turns out, whispers that
this particular vaccine fails to thwart the devastating
possibility of pneumococcal meningitis infection in some
kids were confirmed by a study in the August issue of
The Journal of Infectious Diseases.
Even though a particularly high-risk
model of implant was taken off of the market several
years ago, having any of these devices increases the
risk of meningitis by some 16 times. The study supported
the use of the new seven-valent pneumococcal conjugate
vaccine (PCV-7) in kids under six — findings that
ran counter to the current Health Canada recommendations
that call for the routine use of the traditional 23-valent
pneumococcal polysaccharide vaccine (PPV-23) for children
aged five and over. Health Canada guidelines do state,
however, that PCV-7 is "not contraindicated" in this
age group.
Dr Markus Rose and colleagues from
J W Goethe University in Frankfurt, Germany looked at
immune responses to pneumococcal vaccination in 174
infants and children who'd received cochlear implants.
Patients were divided into three groups, based on whether
their hearing impairment resulted from meningitis, structural
abnormalities of the head, or an unknown cause. Infants
less than two-years-old received PCV-7, which contains
bits of the seven most common types of S pneumoniae.
Those aged two to five received either PCV-7 or the
traditional PPV-23, which contains the antigenic bits
from 23 types of S pneumoniae, while those over
five-years-old received PPV-23.
The serum levels of three types
of immunoglobulins (IgG, IgG1 and IgM) and S pneumoniae
antibodies were measured before and six weeks after
vaccination.
Vaccination with PCV-7 or PPV-23
did kick-start antibody production enough to be protective
against future brushes with S pneumoniae. But
the antigenic response to PPV-23 was weaker than to
PCV-7 in all the age groups, especially kids aged two
to five. Further, kids with a history of meningitis
had "significantly diminished" immunoglobulin and serum
pneumococcal antibody levels compared to the other hearing-impaired
groups and healthy controls. Currently, PPV-23 is used
in vaccination of children over age five. But Dr Rose
and his colleagues said, "PCV-7 should be administered
to all cochlear implant recipients younger than six
years and older than six years who are at
an increased risk for bacterial meningitis." Approximately
2,000 devices have been implanted since 1987 in Canada.
Under the current Health Canada guidelines, which defer
to the PPV-23 vaccine, there have been five cases of
bacterial meningitis and one death from the disease
reported up to the end of 2002.
|
