Effectiveness of 23-Valent Pneumococcal Polysaccharide Vaccine Against Invasive Disease and Hospital-Treated Pneumonia Among People Aged ≥65 Years: A Retrospective Case-Control Study
CID
Effectiveness of 23-Valent Pneumococcal Polysaccharide Vaccine Against Invasive Disease and Hospital-Treated Pneumonia Among People Aged ≥65 Years: A Retrospective Case-Control Study
Maya Leventer-Roberts 1
Becca S. Feldman
Ilan Brufman
Chandra J. Cohen-Stavi
Moshe Hoshen
Ran D. Balicer 0
0 Department of Epidemiology, Faculty of Health Sciences, Ben Gurion University , Be'er Sheva , Israel
1 Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai , New York , New York
Background. Streptococcus pneumoniae contributes considerably to the burden of pneumonia and invasive pneumococcal disease (IPD), with the effectiveness of the 23-valent pneumococcal polysaccharide vaccine (PPSV23) for preventing all-cause pneumonia still undetermined. The aim of this study was to control for common biases and confounders associated with previous observational studies and to assess PPSV23 vaccine effectiveness in preventing IPD and the most resource-intensive type of community-acquired pneumonia, hospital-treated pneumonia (HTP). Methods. This was a retrospective case-control study nested in a population-based cohort, with age-, sex-, and risk-matched controls as the base case. Demographic information, laboratory data, and diagnoses were extracted from the chronic disease registry and from inpatient and outpatient records in the Clalit Health Services database. Vaccine effectiveness for PPSV23 was assessed using multivariable conditional logistic regression. Subgroup, sensitivity, and secondary analyses were conducted to validate findings. Results. A total of 470 070 individuals aged ≥65 years were members of Clalit Health Services during the study period (1 January 2007 through 31 December 2010). The case cohort consisted of 212 participants with IPD and 23 441 with HTP. The adjusted association between vaccination and IPD was protective (odds ratio [OR], 0.58; 95% confidence interval [CI], .41-.81), whereas there was no demonstrated protective effect between vaccination and HTP (OR, 1.01; 95% CI, .97-1.04). The sensitivity analysis and all but 1 subgroup analysis provided consistent results to the base case. Conclusions. The PPSV23 vaccine is effective against the most severe invasive forms of pneumococcal disease, but the lack of effectiveness of PPSV23 in protecting against all-cause HTP should be considered for future vaccine policies. Worldwide, Streptococcus pneumoniae contributes considerably to morbidity and mortality due to bacterial
vaccine effectiveness; pneumococcal vaccination; invasive pneumococcal disease; pneumonia
-
respiratory tract infection and invasive disease [
1, 2
].
An estimated 23%–50% of community-acquired
pneumonia (CAP) cases are caused by S. pneumoniae [
3, 4
].
Severe forms of CAP may require hospitalization and
extended hospital stays, which adds to the disease burden
[
5, 6
]. Those at increased risk for the rarer, but more
serious, invasive pneumococcal disease (IPD) include
older and immunocompromised adults [
2, 5, 7
].
There are 2 types of vaccines administered for
preventing pneumococcal infections. The 23-valent
pneumococcal polysaccharide vaccine (PPSV23)
consists of serotypes corresponding to 85%–90% of IPD isolates
[
8
], and the 13-valent pneumococcal conjugate vaccine
(PCV13) consists of serotypes corresponding to >60% of disease
isolates in children [
9
]. PPSV23 potentially affords broader
protection against IPD because it covers a larger
proportion of serotypes found in IPD cases; however, it lacks
the superior immunogenicity of the conjugated vaccine
[
10–12
].
The current recommendations in Israel and other countries
are to give PPSV23 to all adults aged ≥65 years and those
aged <65 years with certain risk factors, and to administer
PCV13 in the pediatric population [
13
]. Several randomized
controlled trials and meta-analyses have reproduced initial
findings that PPSV23 is likely to be effective in preventing IPD
among adults [
14–18
], and a few studies have suggested that
PPSV23 is possibly effective in preventing pneumococcal
pneumonia [
19, 20
]. Conversely, there have also been multiple
reviews and meta-analyses indicating that there is insufficient
evidence [
21–23
] and significant methodological shortcomings
limiting conclusions about PPSV23’s effectiveness against IPD
and pneumonia [
24, 25
]. Observational studies assessing
vaccination effectiveness in general populations demonstrated both
effectiveness and a lack thereof [
4, 8, 26–28
]. Recently, an
observational study by Ochoa-Gondar et al [
29
] found that PPSV23
was protective for all-cause pneumonia and pneumococcal
pneumonia among a subgroup of patients more recently
vaccinated. Given the inconsistent evidence on the effectiveness of PPSV23
and the initial results reporting efficacy of PCV13 against
pneumococcal pneumonia in an adult population [
30
], the question has
been raised whether PPSV23 could be complemented with, or
replaced by, PCV13 [
12 (...truncated)