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- Community-acquired pneumonia
- severe pneumonia
- complicated pneumonia
- bacterial infection
- paediatric lung disease
We thank Dr Das for his letter1 regarding our paper on the management of severe community-acquired pneumonia in children.2 He questions our suggestion that both Haemophilus influenzae type b (Hib) conjugate and pneumococcal conjugate (PCV) vaccines could be given to Asian children living in developing countries on the grounds that the incidence of infections due to Hib and the pneumococcal serotypes included in PCV is low. He also states that there is no clear demonstration that either vaccine is effective, and the risk of replacement phenomena is a significant limitation.
Regarding the burden of Hib infection, data show that Hib is significantly more important in Asia than previously thought mainly because a number of cases are not identified by the short-term administration of low-dose antibiotics used in many countries, which often prevents the microbiological diagnosis of Hib infections.3 Studies carried out in Indonesia and Bangladesh indicate that the clinical efficacy of Hib vaccine is much greater than that calculated on the basis of the reduction in bacteriologically confirmed cases,3 thus suggesting a higher incidence of Hib diseases and the theoretical efficacy of vaccination. Furthermore, the available data (including data from Asia) indicate that the Hib vaccine has an 18% overall effect on radiologically confirmed pneumonia.4
The emergence of new H influenzae serotypes after Hib vaccine administration (including those that cannot be typed) has been documented in some, but not all geographical areas. Furthermore, their relevance is marginal when set against the advantage of vaccination. All the studies have shown that the reduction in invasive Hib diseases is significantly greater than the increase in those due to new serotypes.5 The same is true of PCV, whose role in conditioning replacement has probably been overestimated because the emergence of the new 19A serotype has also been observed when the vaccine was not used.6 Moreover, the importance of PCV in reducing the incidence of pneumococcal community-acquired pneumonia by about 23% in a low-income, low-mortality developing Asian country, the Philippines, has recently been clearly demonstrated by Lucero et al.7
Finally, the use of Hib vaccines and PCV can induce significant herd immunity, thus justifying the conclusion that both should used in Asian children.