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Babies whose mothers were vaccinated against
measles as children may
be more susceptible to measles than those born
to mothers who were not vaccinated. The investigators believe
that this might have contributed to the increase in the number
of cases of measles in the US between 1989 and 1991.
Infants up to 15 months of age represented
only 2% of the US population between 1989 and 1991, according
to the Centers for Disease Control. But this group of infants
accounted for 24% of the 55,622 cases of measles reported
during that period.
Women who are vaccinated against the
disease have lower levels of infection-fighting antibodies
in their blood than those who were infected naturally. Therefore,
vaccinated mothers pass
on less immunity to their infants, and these children
may be more susceptible to infection.
To test this theory, Papania's team interviewed
the mothers of 128 infants who were 15 months or younger and
had been exposed to measles between 1990 and 1992. In infants
whose mothers were born after the measles vaccine was licensed
in 1963, the measles rate was 33%. In infants born to older
mothers, the rate was only 12%.
Pediatrics
November 1999;104:e59
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