The impact of 10-valent Pneumococcal Conjugate Vaccine on the
incidence of radiologically-confirmed pneumonia and clinically-defined
pneumonia in Kenyan children: an interrupted time series analysis
incidence of radiologically-confirmed pneumonia and clinically-defined
pneumonia in Kenyan children: an interrupted time series analysis
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Background
Pneumococcal conjugate vaccines (PCV) are highly protective against
invasive pneumococcal disease caused by vaccine serotypes but the burden
of pneumococcal di
sease in developing countries is dominated by
pneumonia, most of which is non
-
bacteraemic. We examined the impact of
10
-
valent PCV on pneumonia incidence.
Methods
We linked prospective hospital surveillance for clinically
-
defined WHO
severe or very
-
sev
ere pneumonia at Kilifi County Hospital from 2002
-
2015
to population surveillance at Kilifi Health and Demographic Surveillance
System, comprising 45,000 children aged <5 years. Chest radiographs were
read according to a WHO standard. A 10
-
valent pneumococ
cal non
-
typeable
Haemophilus influenzae protein D conjugate vaccine (PCV10) was introduced
in Kenya in January 2011. In Kilifi, there was a 3
-
dose catch
-
up campaign
for infants and a 2
-
dose catch
-
up campaign for children aged 1
-
4 years
between January and
March 2011. We estimated the impact of PCV10 on the
incidence of clinically
-
defined and radiologically
-
confirmed pneumonia
through interrupted time series analysis accounting for seasonal and
temporal trends.
Findings
At the start of the study, in 2002
/3, the incidence of admission with
clinically
-
defined pneumonia was 21·7/1000/year in children aged 2
-
59
months. By the end of the catch
-
up campaign, 61·1% of children aged 2
-
11
months had received ≥2 doses and 62·3% of children aged 12
-
59 months had
rece
ived ≥1 dose of PCV10. Across the whole 13
-
years of surveillance the
incidence of clinically
-
defined pneumonia declined by 0.5% per month,
independent of vaccine introduction; in contrast, there was no secular
trend in the incidence of radiologically
-
confi
rmed pneumonia over 8 years
of study.
After adjusting for secular trend and season, incidence rate ratios for
admission with radiologically
-
confirmed pneumonia, clinically
-
defined
pneumonia, and diarrhoea (control condition), associated temporally with
PCV10 introduction and the catch
-
up campaign, were 0·52 (95% CI 0·32
-
0·86), 0·73 (95% CI 0·54
-
0·97) and 0·63, (95% CI 0·31
-
1·26),
respectively. Immediately prior to PCV10 introduction the annual
incidence of clinically
-
defined pneumonia was 12·2/1000; this
was reduced
by 3·3/1000 at the point of PCV10 introduction.
Interpretation
Over 13 years, hospitalisations for clinically
-
defined pneumonia declined
progressively at Kilifi County Hospital but fell abruptly by 27% in
association with PCV10 introductio
n. The incidence of radiologically
-
confirmed pneumonia was stable in the pre
-
vaccine period but fell by 48%
in association with PCV10 introduction. The hospital burden of childhood
pneumonia in Kilifi, Kenya, has been reduced substantially by the
introduct
ion of PCV10.
Pneumococcal conjugate vaccines (PCV) are highly protective against
invasive pneumococcal disease caused by vaccine serotypes but the burden
of pneumococcal di
sease in developing countries is dominated by
pneumonia, most of which is non
-
bacteraemic. We examined the impact of
10
-
valent PCV on pneumonia incidence.
Methods
We linked prospective hospital surveillance for clinically
-
defined WHO
severe or very
-
sev
ere pneumonia at Kilifi County Hospital from 2002
-
2015
to population surveillance at Kilifi Health and Demographic Surveillance
System, comprising 45,000 children aged <5 years. Chest radiographs were
read according to a WHO standard. A 10
-
valent pneumococ
cal non
-
typeable
Haemophilus influenzae protein D conjugate vaccine (PCV10) was introduced
in Kenya in January 2011. In Kilifi, there was a 3
-
dose catch
-
up campaign
for infants and a 2
-
dose catch
-
up campaign for children aged 1
-
4 years
between January and
March 2011. We estimated the impact of PCV10 on the
incidence of clinically
-
defined and radiologically
-
confirmed pneumonia
through interrupted time series analysis accounting for seasonal and
temporal trends.
Findings
At the start of the study, in 2002
/3, the incidence of admission with
clinically
-
defined pneumonia was 21·7/1000/year in children aged 2
-
59
months. By the end of the catch
-
up campaign, 61·1% of children aged 2
-
11
months had received ≥2 doses and 62·3% of children aged 12
-
59 months had
rece
ived ≥1 dose of PCV10. Across the whole 13
-
years of surveillance the
incidence of clinically
-
defined pneumonia declined by 0.5% per month,
independent of vaccine introduction; in contrast, there was no secular
trend in the incidence of radiologically
-
confi
rmed pneumonia over 8 years
of study.
After adjusting for secular trend and season, incidence rate ratios for
admission with radiologically
-
confirmed pneumonia, clinically
-
defined
pneumonia, and diarrhoea (control condition), associated temporally with
PCV10 introduction and the catch
-
up campaign, were 0·52 (95% CI 0·32
-
0·86), 0·73 (95% CI 0·54
-
0·97) and 0·63, (95% CI 0·31
-
1·26),
respectively. Immediately prior to PCV10 introduction the annual
incidence of clinically
-
defined pneumonia was 12·2/1000; this
was reduced
by 3·3/1000 at the point of PCV10 introduction.
Interpretation
Over 13 years, hospitalisations for clinically
-
defined pneumonia declined
progressively at Kilifi County Hospital but fell abruptly by 27% in
association with PCV10 introductio
n. The incidence of radiologically
-
confirmed pneumonia was stable in the pre
-
vaccine period but fell by 48%
in association with PCV10 introduction. The hospital burden of childhood
pneumonia in Kilifi, Kenya, has been reduced substantially by the
introduct
ion of PCV10.
Date Issued
2019-03
Date Acceptance
2018-10-23
Citation
The Lancet Global Health, 2019, 7 (3), pp.e337-e346
ISSN
2214-109X
Publisher
Elsevier
Start Page
e337
End Page
e346
Journal / Book Title
The Lancet Global Health
Volume
7
Issue
3
Copyright Statement
© 2019 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.
Sponsor
Wellcome Trust
Wellcome Trust
Identifier
https://www.sciencedirect.com/science/article/pii/S2214109X18304911
Grant Number
091758/B/10/Z
202800/Z/16/Z
Subjects
0605 Microbiology
1117 Public Health and Health Services
Publication Status
Published
Date Publish Online
2019-02-14