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[Infectious Diseases
News Brief]
Influenza Immunization: Ontario
Ontario's decision to make the influenza vaccine available at no charge to
all its citizens for this year's flu season has sparked debate in the public
health community. The "pro" side argues that at best, this strategy will be
a major advance in influenza control; at worst, it will reduce the burden
of influenza but will not be efficient, at which point it can be modified
appropriately. The potential additional benefits include protecting vulnerable
populations, improving high-risk coverage, reducing community transmission
and improving preparedness for a pandemic. The "con" side argues that given
the cost of the Ontario program ($38 million) and the quality of information
available, it is unlikely universal vaccination will be introduced elsewhere.
As clearly stated by the Ontario government, the aim is to ease pressure on
emergency services during the influenza season. There is absolutely no evidence
that universal vaccination has ever achieved such a goal.
Source: Canadian Medical Association Journal, Vol 164, No 1, January 9,
2001
Meningococcal Disease: Quebec
A gradual increase in the number of cases of meningococcal disease (MCD) reported
to the public health authorities was observed in Quebec in the late 1980s.
In an attempt to contain this outbreak, Quebec decided to immunize 1.9 million
children between the ages of 6 months and 20 years. The program actually managed
to reach 84% of that cohort. The program, which ran from December 1992 to
March 1993, provided a perfect opportunity to study the effectiveness of the
vaccine and such a program. Researchers studied the incidence of the disease
in the province over the following 5 years, comparing rates among those who
had been immunized versus those who had not. The incidence of serogroup C
disease decreased after the mass immunization campaign, from 1.4 per 100,000
in 1990-1992 to 0.3 per 100,000 in 1993-1998, and the overall incidence of
other serogroups remained stable at 0.7 per 100,000. Vaccine effectiveness
was strongly related to age at vaccination: 83% for ages 15-20 years, 75% for
ages 10-14 years, and 41% for ages 2-9 years. The researchers concluded that
serogroup C polysaccharide vaccine is effective for controlling outbreaks
in teenaged individuals but should not be used in children < 2 years
of age. Ultimately, cost-effectiveness should be the criterion for deciding
which of the polysaccharide or conjugate vaccines should be recommended for
different age groups. Results of randomized trials and epidemiologic studies
on conjugate vaccines are urgently needed for comparison purposes.
Source: Journal of the American Medical Association, Vol 285, No 2, January
10, 2001
Poliomyelitis: Dominican Republic and Haiti
The Pan American Health Organization has been monitoring an outbreak of poliomyelitis
in Haiti and the Dominican Republic and has concluded that the situation appears
to be under control and has urged countries not to retreat from achieving
and maintaining high vaccination coverage. One case of poliomyelitis due to
a Polio Type 1 vaccine-derived virus was confirmed in Haiti in August 2000.
Subsequent intensive case searches throughout the country were conducted during
October, November and December 2000, and 14 suspected cases were investigated
epidemiologically, clinically and by the laboratory. So far, results have
been completed for 6 of these cases, all negative for poliomyelitis. Results
for the other 8 cases are expected within upcoming weeks. In the Dominican
Republic, there have been 6 poliomyelitis cases due to a vaccine-derived poliovirus
Type 1. Intensive investigation over the last few weeks did not uncover additional
cases. Two weeks ago the government there vaccinated 1.2 million children
during a national campaign. The Pan American Health Organization sent 16 epidemiologists
to support the health ministries in the Dominican Republic and Haiti. The
outbreak caused serious concern because the Western Hemisphere has been free
of wild poliovirus circulation since 1991, and because the virus identified
is an unusual derivative of the Sabin type 1 oral poliovirus vaccine (OPV).
Source: Pan American Health Organization, Press Release, January 8, 2001
The details given are for information only and may be
very provisional. Where incidents are considered of national importance and
are ongoing, the initial report will be updated as new information becomes
available.
[Infectious Diseases
News Brief]
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