Are the pneumococcal polysaccharide vaccines effective? Meta-analysis of the prospective trials

Abstract

The objective was to review the evidence of effectiveness of the polyvalent polysaccharide pneumococcal vaccine from prospective properly randomised controlled trials comparing pneumococcal vaccines with placebo in subjects who are immunocompetent and those likely to have an impaired immune system.Databases searched included the Cochrane Library, (issue 2, 2000), MEDLINE (1966-August 2000), PubMed (to August 2000) and EMBASE ( to August 2000). Reference lists of reports and reviews were also searched. To be included in the analysis, a study had to have been a prospective randomised comparison of a polysaccharide pneumococcal vaccine (any valency) and to have a placebo or no treatment comparison group. Papers had to report important clinical outcomes, such as rates of pneumonia, pneumococcal pneumonia, lower respiratory tract infections, pneumonia deaths or bacteraemia. Serological outcomes were not sought. Thirteen randomised comparisons with over 45,000 subjects were identified in an extensive literature review. Eight studies had a quality score of 3 or more on a scale of 1 to 5. In three comparisons with 21,152 immunocompetent subjects (South African gold miners, New Guinea highlanders) pneumococcal vaccination was effective in reducing the incidence of all-cause pneumonia (relative risk 0.56, 95% confidence interval 0.47 to 0.66), pneumococcal pneumonia (0.16; 0.11 to 0.23), pneumonia deaths (0.70; 0.50 to 0.96) and bacteraemia (0.18; 0.09 to 0.34). In ten comparisons in over 24,000 people who were elderly or likely to have impaired immune systems, pneumococcal vaccination was without effect for any outcome.Present guidelines recommend pneumococcal vaccination for "high-risk" groups. There is no evidence from randomised trials that this is of any benefit.

Efficacy of pneumococcal vaccination in adults: a meta-analysis

“…Several meta-analyses reported protective effects of the vaccine on all-cause pneumonia in subgroups, for example lowrisk groups or populations from lower income countries. 11,16,19 Some previous meta-analyses agreed with our finding of no compelling evidence for the vaccine being associated with a reduced risk of all-cause pneumonia, particularly among elderly or chronically ill people. 7,16,17,19,22 Conclusions for other outcomes were often conflicting, especially for invasive pneumococcal disease.…”

“…11,16,19 Some previous meta-analyses agreed with our finding of no compelling evidence for the vaccine being associated with a reduced risk of all-cause pneumonia, particularly among elderly or chronically ill people. 7,16,17,19,22 Conclusions for other outcomes were often conflicting, especially for invasive pneumococcal disease. A recent Cochrane review 7 found strong evidence supporting the vaccine's efficacy against invasive pneumococcal disease, reporting a combined odds ratio of 0.26 (95% CI 0.15-0.46).…”

“…[4][5][6] Meta-analyses of controlled clinical trials have produced conflicting results of the efficacy of unconjugated pneumococcal polysaccharide vaccine. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] The lack of consistency between results reported from observational studies and controlled trials is another reason why the efficacy of the vaccine remains controversial. Empirical studies have shown that inadequate quality of clinical trials can lead to biases that distort their results.…”

Guidelines for the management of adult lower respiratory tract infections

“…The efficacy of the pneumococcal polysaccharide vaccine has been evaluated in five meta-analyses, or systematic reviews [314][315][316][317][318]. The quality, as well as the results, of these metaanalyses/systematic reviews differs, due to when they were performed and differences in methodology.…”

El dilema sobre el coste-efectividad de la vacuna antineumocócica sigue abierto

“…Para ello seleccionaron trece estudios de las características señaladas en los que además se reflejaran hechos clínicos relevantes como las tasas de neumonía global, neumonía neumocócica, de infección respiratoria baja, bacteriemia y muertes por neumonía. Concluyen que este tipo de vacunas son efectivas en la población inmunocompetente para disminuir la incidencia global de neumonías y el resto de las tasas mencionadas y que en cambio no existe evidencia de beneficio para la población con alguna alteración del sistema inmune 8 . Sin e m b a rgo, debido a las diferencias en la capacidad del sistema inmunitario para hacer frente a la infección neumocócica, la efectividad de estas vacunas varía según el tipo de inmunodepresión, por lo que estos ensayos deberían estar categorizados según las características de los pacientes estudiados para poder establecer comparaciones.…”