A Study of Streptococcus Pneumonia Colonisation and Invasive Disease in Cambodian Children
Condition: Streptococcal Pneumonia
MeSH terms: Pneumonia; Pneumonia, Pneumococcal
Study type: Observational

Summary: 
      Streptococcus pneumoniae (the pneumococcus) remains a leading cause of childhood mortality
      and morbidity. Between 2007 and 2012, Angkor Hospital for Children (AHC), Siem Reap, Cambodia
      documented that S. pneumoniae was responsible for around 10% of bloodstream infections in
      hospitalised children, with a case fatality rate of 15.6%.

      The use of pneumococcal conjugate vaccines (PCV), covering between 7 and 13 of the >90
      pneumococcal serotypes, has resulted in significant declines in invasive pneumococcal disease
      (IPD) incidence in countries where they are included in routine childhood immunisation
      schedules. Paediatric radiologic pneumonia incidence is also reduced by PCV, but the impact
      on clinical pneumonia is minimal. The vaccines have had an effect on reducing the burden of
      drug resistant IPD, although this may not be sustained. Given the large number of serotypes
      not included in the current PCV formulations, it is not surprising that initial declines in
      overall IPD incidence have been eroded by, for the time being, small increases in IPD due to
      non-vaccine serotypes. To date most data on this serotype replacement disease has come from
      high-income countries. It less clear how much serotype replacement will occur in low and
      middle income countries, where pre-PCV disease incidence is generally higher and other
      factors, such as unregulated antimicrobial consumption, may play a role in encouraging
      non-vaccine serotype infections.

      Nasopharyngeal colonisation by S. pneumoniae is common in childhood and is an essential
      prerequisite for invasive disease. Surveillance of pneumococcal colonisation can provide
      important data regarding serotype replacement and disease-associated serotypes, and may also
      allow prediction of likely IPD incidence changes post-vaccine introduction. A recent study of
      pneumococcal colonisation in children attending the AHC out-patients has documented an
      overall colonisation prevalence of approximately 65%.

      In January 2015, Cambodia will introduce the 13-valent PCV (PCV13; serotypes covered 1, 3, 4,
      5, 6A, 6B, 7F, 9V, 14, 18C, 19F, 19A, 23F). The vaccine will be rolled out nationally with a
      3+0 dosing schedule (6, 10 and 14 weeks) and no catch up campaign. There is no robust
      national surveillance system in place to monitor the effects of PCV13 introduction.
    


Intervention name(s): Prospective study; Prospective study; Cross-sectional surveys
Intervention type(s): Other; Other; Other
Intervention description(s): To identify and characterise patients with culture proven invasive pneumococcal disease or probable bacterial meningitis over the first three years after PCV13 introduction in Cambodia in January 2015.; To identify and characterise patients hospitalised with clinical and/or radiologic pneumonia over the first three years after PCV13 introduction in Cambodia in January 2015; Three annual surveys, enrolling 450 children each year, will be done to identify and characterise pneumococcal nasopharyngeal colonisation in AHC out-patient department (OPD) attendees
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Group1: This is a prospective study to identify and characterise patients with culture
        proven invasive pneumococcal disease or probable bacterial meningitis over the first three
        years after PCV13 introduction in Cambodia in January 2015.

        Group2: This is a prospective study to identify and characterise patients hospitalised with
        clinical and/or radiologic pneumonia over the first three years after PCV13 introduction in
        Cambodia in January 2015.

        Group3: Three annual surveys, enrolling 450 children each year, will be done to identify
        and characterise pneumococcal nasopharyngeal colonisation in AHC out-patient department
        (OPD) attendees.
      
Keywords: Streptococcal Pneumonia; Pneumococcal Conjugate Vaccine