Abstract
SummaryBackgroundThe Gambia introduced seven-valent pneumococcal conjugate vaccine (PCV7) in August 2009, followed by PCV13 in May, 2011, using a schedule of three primary doses without a booster dose or catch-up immunisation. We aimed to assess the long-term impact of PCV on disease incidence.MethodsWe did 10 years of population-based surveillance for invasive pneumococcal disease (IPD) and WHO defined radiological pneumonia with consolidation in rural Gambia. The surveillance population included all Basse Health and Demographic Surveillance System residents aged 2 months or older. Nurses screened all outpatients and inpatients at all health facilities using standardised criteria for referral. Clinicians then applied criteria for patient investigation. We defined IPD as a compatible illness with isolation of Streptococcus pneumoniae from a normally sterile site (cerebrospinal fluid, blood, or pleural fluid). We compared disease incidence between baseline (May 12, 2008–May 11, 2010) and post-vaccine years (2016–2017), in children aged 2 months to 14 years, adjusting for changes in case ascertainment over time.FindingsWe identified 22 728 patients for investigation and detected 342 cases of IPD and 2623 cases of radiological pneumonia. Among children aged 2–59 months, IPD incidence declined from 184 cases per 100 000 person-years to 38 cases per 100 000 person-years, an 80% reduction (95% CI 69–87). Non-pneumococcal bacteraemia incidence did not change significantly over time (incidence rate ratio 0·88; 95% CI, 0·64–1·21). We detected zero cases of vaccine-type IPD in the 2–11 month age group in 2016–17. Incidence of radiological pneumonia decreased by 33% (95% CI 24–40), from 10·5 to 7·0 per 1000 person-years in the 2–59 month age group, while pneumonia hospitalisations declined by 27% (95% CI 22–31). In the 5–14 year age group, IPD incidence declined by 69% (95% CI −28 to 91) and radiological pneumonia by 27% (95% CI −5 to 49).InterpretationRoutine introduction of PCV13 substantially reduced the incidence of childhood IPD and pneumonia in rural Gambia, including elimination of vaccine-type IPD in infants. Other low-income countries can expect substantial impact from the introduction of PCV13 using a schedule of three primary doses.FundingGavi, The Vaccine Alliance; Bill & Melinda Gates Foundation; UK Medical Research Council; Pfizer Ltd.
Highlights
Global childhood deaths due to pneumococcal disease are estimated to have fallen from 826 000 in 20001 to 318 000 in 2015.2 Introduction of pneumococcal conjugate vaccines (PCV) likely contributed to this decrease
A schedule with two primary doses and a booster dose was used in South Africa, whereas a three-dose schedule without a booster dose was used in Kenya, accompanied by a catch-up campaign in children younger than 5 years old
Added value of this study This study provides the first evidence of long-term PCV impact when immunisation is introduced with the standard three-dose schedule without a booster or catch-up dose, as is the norm in almost all low-income countries. 8 years after the introduction of PCV7 or PCV13, this 10-year population based surveillance study observed a 92% reduction in the incidence of invasive pneumococcal disease (IPD) due to vaccinetypes in the [2–59] month age group, an 80% reduction in all IPD, and no significant change in non-vaccine type IPD
Summary
Global childhood deaths due to pneumococcal disease are estimated to have fallen from 826 000 in 20001 to 318 000 in 2015.2 Introduction of pneumococcal conjugate vaccines (PCV) likely contributed to this decrease. Despite 60 low-income countries having introduced PCV, data are limited on vaccine impact in these settings. In South Africa, and Kenya, substantial reductions in invasive pneumococcal disease (IPD) were observed after the introduction of PCV.[3,4] A schedule with two primary doses and a booster dose was used in South Africa, whereas a three-dose schedule without a booster dose was used in Kenya, accompanied by a catch-up campaign in children younger than 5 years old. Most low-income countries use a schedule with three primary doses without a booster or catch-up immunisation, and there is little information on this schedule’s effectiveness in these countries.
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