Abstract
ABSTRACTBackground: In 2010, Greenland introduced the 13-valent pneumococcal conjugate vaccine (Prevnar 13®– PCV-13) in the childhood immunisation program. The authors aimed to evaluate the impact of PCV-13 on nasopharyngeal carriage of bacteria frequently associated with respiratory infections in children.Method: In 2013 a cross-sectional population-based study of nasopharyngeal carriage was conducted among Greenlandic children aged 0–6 years and results were compared with an equivalent study from 2011. Nasopharyngeal swab samples were tested for Streptococcus pneumoniae, non-typeable Haemophilus influenzae, Moraxella catarrhalis and Staphylococcus aureus. Pneumococcal serotyping was performed by Quellung reaction and serotype-specific antisera. Statistical analysis included logistic regression models, adjusting for known risk factors.Result: A total of 377 nasopharyngeal samples were collected. Overall carriage rate of S. pneumoniae remained unchanged from 2011 to 2013 (51% and 56%, p=0.13), but significant serotype shifts were observed among both vaccinated and unvaccinated children with marked reductions in carriage of vaccine-type pneumococci, counterbalanced by increasing carriage of non-vaccine types. Carriage rate of S. aureus decreased significantly among vaccinated children whereas that of M. catarrhalis increased.Conclusion: PCV-13 introduction in Greenland is associated with significant changes in nasopharyngeal bacterial carriage. Continued surveillance is warranted to clarify whether these changes are persistent, and affect the pattern of respiratory and invasive diseases in Greenland.
Highlights
The Inuit population of Greenland suffers from high rates of respiratory infections and invasive bacterial diseases [1], causing higher morbidity and mortality than among non-Inuit [1,2,3,4,5,6,7].Nasopharyngeal bacterial carriage is the essential precursor of these infections with Streptococcus pneumoniae, non-typeable Haemophilus influenzae (NTHi), Moraxella catarrhalis, and Staphylococcus aureus as the most clinically relevant bacteria [8,9,10,11]
the 13-valent pneumococcal conjugate vaccine (PCV-13) introduction in Greenland is associated with significant changes in nasopharyngeal bacterial carriage
Ethnicity was based on the parents’ place of birth. If both parents were born in Greenland, ethnicity was defined as Inuit; one parent born in Greenland and one elsewhere or unknown was defined as a “mixed Inuit”, and no known parents born in Greenland as “other”, which is mainly Danish (Caucasian) ethnicity
Summary
The Inuit population of Greenland suffers from high rates of respiratory infections and invasive bacterial diseases [1], causing higher morbidity and mortality than among non-Inuit [1,2,3,4,5,6,7]. Nasopharyngeal bacterial carriage is the essential precursor of these infections with Streptococcus pneumoniae, non-typeable Haemophilus influenzae (NTHi), Moraxella catarrhalis, and Staphylococcus aureus as the most clinically relevant bacteria [8,9,10,11]. The Inuit populations of Alaska and Canada share the high risk of respiratory infections as well as invasive pneumococcal disease (IPD) [2,14,15]. In Greenland, Inuit have four times as high risk of invasive pneumococcal disease compared with non-Inuit [16]. Carriage rate of S. aureus decreased significantly among vaccinated children whereas that of M. catarrhalis increased
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