Læknablaðið : fylgirit - 01.08.2002, Page 30

ABSTRACTS / 21 ST NORDIC CONGRESS OF ALLERGOLOGY
which are T-cell independent antigens. By conjugating pneumo-
coccal polysaccharides to protein, they have been rendered im-
munogenic in this age group. The pneumococcal conjugate vaccines
(Pnc) have been shown to be safe and induce protective antibody
response in infants at an age when they are unable to respond to
pneumococcal capsular polysaccharides. Vaccine trials in Iceland
have shown that the IgG response to the Pnc is carrier and serotype
specific. The vaccine induced IgG antibodies were functional as
demonstrated with opsonophagocytosis and a good IgG booster
response with avitity maturation indicated memory induction. On
the other hand, naturally aquired immunity may reflect antibodies
that are nonspecific and nonfunctional. Most purified PPS used for
antibody measurements are contaminated with cell wall poly-
saccharide (CWPS), thus antibodies to CWPS which has failed to
demonstrate a prolective role in humans may give false positive
results in ELISA. This may be overcome to some extend by
neutalization with CWPS.
To investigate if the carrier is limitting for the antibody response,
two 11-valent Pnc vaccines, F3 (type 1, 3, 4, 5, 6B, 7F, 9V, 14,18C,
19F and 23F conjugated to tetanus or diphtheria toxoids) and F3bis
(same serotypes but both carrier proteins for 6B, 9V, 18C and 23F)
(Aventis Pasteur) were compared in 146 Icelandic infants. They
were randomized to receive either vaccine at 3,4, 6 and 13 months.
Blood samples were obtained at 3, 7, 13, 14 and 24 months. Both
vaccines were equally safe and induced significant primary and
booster IgG responses. Mixing two conjugates of the less immuno-
genic serotypes containing two protein carriers did not improve the
primary immune response. At 24 months of age the vaccinated
children had higher antibody levels to all 11 serotypes than un-
vaccinaled age-matched controls.
Along with antibody levels, immunological memory is improtant
for long term protection against infection. Avidity maturation and a
rapid IgG response has been used as an indirect indicator of
memory induction. When toddlers were vaccinated with one dose
ofF3bisatl7monthsofage, 95% produced antibodies against 9 of
11 pneumococcal types that were above the level of 0.15 mg/ml.
When they 10 months later, were boosted with PPS vaccine, one log
rise in IgG to 11 serotypes was observed in one week with signifi-
cant increase in avidity, indicating immunological memory al an age
when children usually show marginal response to PPS vaccine.
Other investigators have demaonstrated 97.5% efficacy of Pnc
vaccins against invasive disease and 57% decrease in otitis media
caused by the vaccine serotypes. Prevention of nasopharyngeal
carriage is important for induction of heard immunity and reduc-
tion of transmission but where the vaccines have been used in large
scale, heard immunity has also been observed. A reduction has also
been observed in antibiotic resistant strains as most of those belong
to serotypes that are included in The vaccines.
R 9 - Prevalence of Atopy and Atopic diseases
in lceland
Clausen M
The prevalence of adult atopic diseases in Iceland is lower than in
Western Europe but there are no data concerning children. As part
of the phase-2 of the International Study of Asthma and Allergy in
Children (ISAAC) we investigated the prevalence of atopic
diseases and sensitivity to common allergens, in 10-11 year old
schoolchildren. 946 children and their parents answered question-
naire about atopic diseases. Skin prick tests (SPT) with 6 allergens
were performed on 774 children and signs of atopic eczema
registered. The prevalence of allergic rhinitis was 11% and asthma
9%. The reported prevalence of eczema was 26.9%, however, only
10.3% had signs when inspected. A positive SPT was recorded in
24.9% of the children, i.e. 18.7% to mixed grasses, 12.9% to cat,
3.6% to mixed trees, 2.9% to D. pter, 1.4% to D. farinae and 0.5%
to alternaria. The high prevalence of atopic diseases in children at
10-11 years is surprising as the prevalence in adults is very low in
Iceland. The findings resemble those in developing countries. Other
changes in environmental factors would be operative, however, as
Iceland has had an affluent lifestyle for a considerable time. The
high prevalence of sensitivity to grass pollen may be explained by
the long grass pollen season.
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