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Vaccinating kids
helps prevent adult disease
A vaccination program in Alaska intended to protect young children from a type of
disease-causing bacteria has helped to prevent illness in older kids and adults as well,
researchers report. After Alaska began vaccinating infants against Haemophilus influenzae
type b (Hib) in 1991, cases of the disease dropped in residents aged 10 and older who had
not been immunized.
The fact, that preventing young children from getting infected with Hib lowered the rate
of disease in the overall population, suggests that many adults catch the disease from
young children, as per one of the study's authors.
'Immunizing children with conjugate Hib vaccine not only protects children against
invasive disease caused by Hib, but also appears to protect adults who were never
immunized with Hib vaccine, presumably by reducing the source of adult disease,' said Dr.
Alan J. Parkinson, of the Arctic Investigations Program of the Centers of Disease Control
and Prevention, in Anchorage.
Hib is one of several types of Haemophilus influenzae (H influenzae). Infection with H
influenzae can lead to serious illness, including pneumonia and meningitis, in young
children and in people with weakened immune systems. If left untreated, the infection may
cause brain damage or death. Currently, Hib is the only strain of the bacteria for which
there is a vaccine on the market. Beginning in 1991, the state of Alaska began giving
infants the Hib vaccine. Since then, the rates of vaccination have reached more than 90%
in some years.
After the vaccine program was put in place, the annual rate of new cases of H influenzae
infections among all Alaska residents older than 10 years dropped by 33%, decreasing from
2.1 to 1.4 cases per 100,000 residents, according to Parkinson and colleagues. This
decline was greatest, 71%, in the Native Alaskan population, the researchers report in the
June 21st issue of the Journal of the American Medical Association.
Most of the adults who developed the disease had at least one other medical condition that
could have increased their risk of becoming ill, such as alcohol or drug abuse or
pregnancy. An 80% drop in cases of Hib accounted for most of the drop in disease,
according to the report. In fact, the annual rate of new cases of other strains of H
influenzae actually increased after the vaccination program was put in place.
'This may suggest replacement of Hib by other serotypes,' Parkinson told. 'However, among
children, we have not seen any increase in invasive disease caused by non-b serotypes.'
Still, despite the good news about the drop in Hib cases, the researchers call for careful
monitoring of other strains of H influenzae infections to see whether they are on the rise
in other areas where children are immunized against Hib. |
