Impact of 13-valent pneumococcal conjugate vaccine on laboratory-confirmed pneumococcal meningitis and purulent meningitis among children ˂5 years in Cameroon, 2011-2018.

John Njuma Libwea,Berthe-Marie Njanpop-Lafourcade,Marie Kobela Mbollo,Jean Tageube,Angeline Boula,Paul Koki Ndombo,Bradford Gessner,Rachel Sandrine Kingue Bebey,Mark A Fletcher,Nadesh Taku Ashukem,Joanna Southern,Ali Mohammad,Elizabeth Begier,Shabir Madhi,Eric Gaston Nkolo Mviena,Madeleine Ngo Baleba,Sinata Koulla-Shiro,Rohini Beavon,Silvia Ricci

doi:10.1371/journal.pone.0250010

Abstract

The 13-valent pneumococcal conjugate vaccine (PCV13) entered Cameroon's childhood national immunization programme (NIP) in July 2011 under a 3-dose schedule (6, 10, 14 weeks of age) without any catch-up. We described the impact of PCV13 onserotype distribution among pneumococcal meningitis cases over time. We used laboratory-based sentinel surveillance data to identify meningitis cases among 2- to 59-month-old children with clinically-suspected bacterial meningitis (CSBM) admitted to hospitals in Yaoundé (August 2011-December 2018). Purulent meningitis cases had a cerebrospinal fluid (CSF) white blood cell (WBC) count ≥20 per mm3. Pneumococcal meningitis cases had S. pneumoniae identified from CSF, with serotyping by polymerase chain reaction. Years 2011-2014 were described as early PCV13 era (EPE) and years 2015-2018 as late PCV13 era (LPE) impact periods. Among children hospitalized with CSBM who had a lumbar puncture obtained, there was no significant change from the EPE versus the LPE in the percentage identified with purulent meningitis: 7.5% (112/1486) versus 9.4% (154/1645), p = 0.0846. The percentage of pneumococcal meningitis cases due to PCV13 vaccine-serotype (VST) decreased from 62.0% (31/50) during the EPE to 35.8% (19/53) in the LPE, p = 0.0081. The most frequent pneumococcal meningitis VSTs during the EPE were 6A/6B (30%) and 5 (6%), and during the LPE were 14 (13.2%), 3 (7.6%), 4 (5.6%) and 18C (5.6%). Four to seven years after PCV13 introduction, the proportion of pneumococcal meningitis due to vaccine serotypes has declined, mainly due to reductions of serotypes 6A/6B, 1, 19A, and 23F; nevertheless, PCV13 VSTs remain common. Because the analyzed surveillance system was not consistent or population based, we could not estimate incidence or overall impact; this emphasizes the need for improved surveillance to document further the utility of PCV13 immunization in Cameroon.

Highlights

The 13-valent pneumococcal conjugate vaccine (PCV13) entered Cameroon’s childhood national immunization programme (NIP) in July 2011 under a 3-dose schedule (6, 10, 14 weeks of age) without any catch-up
Among children hospitalized with clinically-suspected bacterial meningitis (CSBM) who had a lumbar puncture obtained, there was no significant change from the early PCV13 era (EPE) versus the late PCV13 era (LPE) in the percentage identified with purulent
Because the analyzed surveillance system was not consistent or population based, we could not estimate incidence or overall impact; this emphasizes the need for improved surveillance to document further the utility of PCV13 immunization in Cameroon

Summary

Introduction

The 13-valent pneumococcal conjugate vaccine (PCV13) entered Cameroon’s childhood national immunization programme (NIP) in July 2011 under a 3-dose schedule (6, 10, 14 weeks of age) without any catch-up. Pneumococcal conjugate vaccine (PCV) was first licensed as a 7-valent vaccine (PCV7). PCV7 was first introduced to infant national immunization programs (NIPs) in the United States in the year 2000, Europe in 2001 and Africa in 2009. Both PCV10 and PCV13, contain serotypes 1 and 5, which are prevalent in developing countries [7, 8], leading to expectations of relatively broad coverage in Sub-Saharan Africa

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