E.K. Mulholland
University of
Melbourne, Australia
Pneumonia remains
the most serious paediatric problem in the world today. It is estimated that of the 10.5
million child deaths that occur in the world each year, about 2 million are due
to pneumonia. Over the past 10
years there have been significant reductions in child mortality in many parts
of the world, but there is little evidence that pneumonia mortality has
fallen. The important bacterial
causes of pneumonia are Streptococcus
pneumoniae (pneumococcus) and Haemophilus
influenzae, particularly type b (Hib); both of these are now vaccine
preventable. Hib vaccines suitable
for use in infants have been available for over 10 years, but their use in the
developing world is limited because of price and knowledge of the burden of
disease (particularly in Asia). It
is difficult to determine the proportion of pneumonia cases that are bacterial,
but vaccine trials indicate that this is higher than previously thought. Pneumococcal polysaccharide vaccines
have been available for many years, but their value for the prevention of
pneumonia in children is unclear.
Pneumococcal conjugate vaccines covering 7-11 of the 90 pneumococcal
serotypes have been developed. The
first pneumococcal conjugate vaccine (7 valent) was licensed in the US in
February 2000. It is effective at
preventing invasive pneumococcal disease and has some impact on otitis
media. Its effectiveness against
pneumonia, particularly in a developing country setting, is unclear. Studies currently underway in South
Africa, Gambia, Philippines and Czech Republic should help clarify the role of
these vaccines. At present
the price of the vaccine is very high and it seems likely to remain high as stringent
US regulatory requirements have discouraged other producers. Large-scale use in developing countries
is still a long way off.