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MONTREAL, Updated 6:39 p.m. EST January 10, 2001 -- A mass
vaccination campaign against meningitis in Quebec in the early 1990s proved
useless in protecting infants who were the most at risk, a study published
today in a major U.S. medical journal reveals.
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And the vaccine that was given probably would no longer be
effective in immunizing the rest of the public should another meningitis
outbreak strike the province, the lead researcher said Tuesday.
Although an
experimental vaccine currently in use in England has been shown to be highly
effective, it's rarely used in the rest of Europe and not available in Quebec,
said Dr. Philippe De Wals, an epidemiologist at the University of Sherbrooke.
Still, De Wals said Quebec is probably better prepared to deal with another
epidemic of the potentially fatal meningococcal disease, in part because of the
findings of his study.
Quebec public-health authorities, for example, now know it would not make
sense to use the old vaccine again if an outbreak occurs.
``We found that the vaccine was effective in the first two years after it
was administered, but we have no evidence that it worked later on,'' De Wals
said in an interview.
``In other words, it was a short-term vaccine.''
At the time that it
was introduced, authorities thought the vaccine would be effective for five
years.
The Quebec government commissioned De Wals to evaluate the long-term impact
of the polysacharide vaccine after its mass immunization campaign of 1992-93.
The results of the study are published in today's Journal of the American
Medical Association.
The researchers discovered that the vaccine was virtually useless in
immunizing children between 6 months and 2 years old.
In fact, eight infants who were vaccinated later developed meningococcal
disease - a bacterial infection that causes inflammation of the tissue in the
brain and spine.
That raises the alarming scenario that the vaccine itself might have been
responsible for infecting the infants.
But De Wals refused to jump to that conclusion: ``We can't say whether the
vaccine caused the illness in these children.''
The vaccine was judged 40-per-cent effective in children between the ages of
2 and 9; 75-per-cent effective among those in the 10-to-14 range; and
85-per-cent effective among those 15 or older.
``It's a vaccine that's excellent for adults and the military, but much less
effective among the youth,'' De Wals said.
Although the incidence of meningococcal disease is low, about one case per
100,000 population, news reports of outbreaks strike fear in the hearts of
parents. It's a terrifying disease that can strike quickly and kill within
hours if untreated.
The provincial government spent up to $30 million immunizing 1.6 million
Quebecers, following clusters of the meningococcal disease reported in all age
groups across the province in 1991-92.
It was the largest immunization effort since the polio-vaccination campaign
of the 1950s.
The researchers noted that the number of cases of the highly contagious
disease dropped markedly in 1993 after the mass immunization, and remained low
thereafter.
For the period covered under the study, Jan. 1, 1990, until Dec. 31, 1998, a
total of 899 cases were reported.
Across Canada each year, there are about 250 to 300 cases of meningococcal
disease, usually during the winter months. Most are isolated cases.
Additional Resources
Copyright 2001 by
The Montreal Gazette. All rights reserved. This material may not be published,
broadcast, rewritten or redistributed.
ALL
INFORMATION, DATA, AND MATERIAL CONTAINED, PRESENTED, OR PROVIDED HERE IS FOR
GENERAL INFORMATION PURPOSES ONLY AND IS NOT TO BE CONSTRUED AS REFLECTING THE
KNOWLEDGE OR OPINIONS OF THE PUBLISHER, AND IS NOT TO BE CONSTRUED OR INTENDED
AS PROVIDING MEDICAL OR LEGAL ADVICE. THE DECISION WHETHER OR NOT TO
VACCINATE IS AN IMPORTANT AND COMPLEX ISSUE AND SHOULD BE MADE BY YOU, AND YOU
ALONE, IN CONSULTATION WITH YOUR HEALTH CARE PROVIDER.