Pneumococcal Carriage in Children under Five Years in Uganda-Will Present Pneumococcal Conjugate Vaccines Be Appropriate?

Abstract

BackgroundPneumonia is the major cause of death in children globally, with more than 900,000 deaths annually in children under five years of age. Streptococcus pneumoniae causes most deaths, most often in the form of community acquired pneumonia. Pneumococcal conjugate vaccines (PCVs) are currently being implemented in many low-income countries. PCVs decrease vaccine-type pneumococcal carriage, a prerequisite for invasive pneumococcal disease, and thereby affects pneumococcal disease and transmission. In Uganda, PCV was launched in 2014, but baseline data is lacking for pneumococcal serotypes in carriage.ObjectivesTo study pneumococcal nasopharyngeal carriage and serotype distribution in children under 5 years of age prior to PCV introduction in UgandaMethodsThree cross-sectional pneumococcal carriage surveys were conducted in 2008, 2009 and 2011, comprising respectively 150, 587 and 1024 randomly selected children aged less than five years from the Iganga/Mayuge Health and Demographic Surveillance Site. The caretakers were interviewed about illness history of the child and 1723 nasopharyngeal specimens were collected. From these, 927 isolates of S. pneumoniae were serotyped.ResultsOverall, the carriage rate of S. pneumoniae was 56% (957/1723). Pneumococcal carriage was associated with illness on the day of the interview (OR = 1.50, p = 0.04). The most common pneumococcal serotypes were in descending order 19F (16%), 23F (9%), 6A (8%), 29 (7%) and 6B (7%). One percent of the strains were non-typeable. The potential serotype coverage rate for PCV10 was 42% and 54% for PCV13.ConclusionAbout half of circulating pneumococcal serotypes in carriage in the Ugandan under-five population studied was covered by available PCVs.

The impact of the ancillary pilus‐1 protein RrgA of Streptococcus pneumoniae on colonization and disease

“…Interestingly, pilus‐1 has not been detected in clonal types expressing these three capsular serotypes (Figure a). We argued that strains belonging to these serotypes have a high invasive disease potential (Lindstrand et al, ; Sjöström et al, ). Mechanisms for this finding are unknown but could depend on a high rate of spread within a population and a short or non‐existent colonization phase.…”

“…These strains do not belong to clonal types expressing pilus‐1. Also interesting is that non‐piliated serotype 3 strains (predominantly of ST180) have increased in the post‐vaccination era as causes of invasive disease, but is low among child carriers (Lindstrand et al, ; Naucler et al, ), even though PCV13 targets serotype 3. We hypothesize that pneumococcal strains having a short duration of colonization and/or are colonizing at low numbers may not lead to immunization and protection against recolonization/infection by the same strain lineage.…”

Paediatric immunisation and chemoprophylaxis in a Ugandan sickle cell disease clinic

“…SCD affects 1–2% of births in Uganda . High under 5‐year mortality of these children is often associated with infections from encapsulated bacteria, including Streptococcus pneumonia ( S. pneumonia ) , Haemophilus influenza b (Hib) and malaria . Vaccination is a key protective measure against S. pneumonia in SCD …”

“…Centralised vaccination records are not maintained. In March 2014, the Ugandan Ministry of Health added PCV‐10 to the schedule of required early childhood vaccines . PCV‐10 administration was extended to age 2 for some children with SCD due to their higher risk of pneumococcal infection …”

“…(Hib) and malaria. [3][4][5][6][7] Vaccination is a key protective measure against S. pneumonia in SCD. [8][9][10] Vaccines, including the pneumococcal 10-valent conjugate vaccine (pneumococcal conjugate vaccine (PCV)-10), antimicrobial prophylaxis with penicillin and anti-malarial prophylaxis, are recommended for children with SCD by the World Health Organization (WHO).…”