Pneumococcal nasopharyngeal carriage in children <5  years of age visiting the pediatric emergency room in relation to PCV7 and PCV13 introduction in southern Israel

Abstract

The 7-valent and the 13-valent pneumococcal conjugate vaccines (PCV7 and PCV13, respectively) were introduced to the Israeli National Immunization plan in July 2009 and November 2010, respectively. Our aim was to assess pneumococcal conjugate vaccines (PCVs) uptake and dynamics in serotype-specific pneumococcal nasopharyngeal (NP) carriage in children <5 years old in southern Israel, during the immediate 5 y following PCV introduction. This was an ongoing, prospective, population-based, active surveillance, from July 2009 through December 2014. PCVs uptake and NP cultures were obtained daily from children seen at the Pediatric Emergency Room for any reason. Overall, 10,702 vaccine status and 7,610 NP swabs were obtained. Both PCV7 and PCV13 uptake were high, reaching~90% by July 2012 and December 2013, respectively. All-pneumococcal carriage rates significantly declined by 10%, from 54.3% in the early-PCV7 period, to 49.1% in the PCV13 impact period. The respective declines for PCV7, 6A and additional PCV13 serotypes carriage rates were 76%, 90% and 66%. In contrast, non-PCV13 serotypes carriage rates increased significantly throughout the study by 71%. All-pneumococcal carriage rates in children <12 months old decreased significantly by 15%, with similar trends observed in other age groups. Initially, all-pneumococcal carriage rates were 45.7%, and 61.9% in Jewish and Bedouin children, respectively (P < 0.001), with a significant 17% reduction throughout the study observed only in Bedouins. While early carriage rates were higher in unvaccinated children compared to vaccinated children, PCV impact on carriage were similar in both groups. In conclusion, a relatively moderate decline in pneumococcal carriage rates, facilitated by a substantial decrease of vaccine-serotypes and increase of non-vaccine serotypes was observed in the immediate period following PCVs introduction in southern Israel.

Impact of Widespread Introduction of Pneumococcal Conjugate Vaccines on Pneumococcal and Nonpneumococcal Otitis Media

“…However, in previous studies that dealt with OM likely to be enriched with complex OM (the POETand COMPAS studies), no significant increase in non-VT disease was observed in vaccinated children [21]. Our group and others have shown an increase in non-VT pneumococcal nasopharyngeal carriage after PCV introduction [34,38]. In contrast, no such increase was shown in complex OM.…”

“…This finding is important since in the crowded Bedouin population (in this aspect, resembling a developing-world population), PCV impact could, in theory, be delayed due to a higher carriage rate, starting from a very young age and expanding to older age, than in the Jewish population, resulting in higher exposure rates both to NTHi and S. pneumoniae [27][28][29][30][31][32]. We previously showed that PCV7/PCV13 reduced vaccine-type (VT) carriage in the 2 ethnic groups in a similar fashion, despite large differences in carriage rates [30,33,34]. Our results are therefore reassuring and suggest that in developing populations where chronic OM cases (including chronic suppurative OM and hearing loss) are prevalent [35], PCVs may prevent a sizeable proportion of the sequelae.…”

Dose-specific effectiveness of 7- and 13-valent pneumococcal conjugate vaccines against vaccine-serotype Streptococcus pneumoniae colonization: a matched, case-control study

“…12 Uptake of PCVs in southern Israel has been described previously. 10 A 2+1 PCV7 schedule (with doses administered at ages 2, 4, and 12 months) was introduced in July, 2009, with a catch-up campaign among children under 2 years of age. Beginning in November, 2010, PCV13 replaced PCV7 without additional catch-up.…”

“…Previous pneumococcal vaccination (number of PCV7 and PCV13 doses) were ascertained from children's medical records. 10 Nasopharyngeal samples were obtained via dacron-tipped swabs and plated within 16 hours on 5% sheep blood/5.0µg gentamicin agar media, and incubated for 48 hours at 35ºC. Pneumococcal identification was based on alpha-hemolysis and optochin inhibition, and confirmed by slide agglutination.…”

“…Long-term population-based surveillance in southern Israel has provided a window into pneumococcal colonization among children in this setting amid PCV7/13 implementation. 10 To guide scheduling considerations, we estimated PCV direct effects against vaccine-serotype colonization according to doses-received-for-age in an individually matched, case-control study.…”