Prevention Of Invasive Pneumococcal Disease Research Articles

Additive preventive effect of influenza and pneumococcal vaccines in elderly persons.

In 1999, all individuals > or = 65 yrs of age (n=258,754) in Stockholm County, Sweden, were offered influenza and pneumococcal vaccination in a prospective study on the effectiveness of these vaccines in reducing the need for hospital treatment and death due to influenza, pneumonia and invasive pneumococcal disease (IPD). Data on hospitalisation and mortality during 1 yr were obtained from the administrative database in Stockholm County Council. Vaccination was performed in 124,702 (48%) subjects; 72,107 had both vaccines, 29,346 only had the influenza vaccine and 23,249 only had the pneumococcal vaccine. Compared with the unvaccinated cohort, a lower incidence of hospitalisation for all endpoint diagnoses was seen in vaccinated persons. An additive effectiveness of vaccination was seen when both vaccines were given, with a reduction of hospital admissions for influenza (37%), pneumonia (29%) and IPD (44%). In-hospital mortality for pneumonia was significantly lower in those who received both vaccines, than in unvaccinated persons. To conclude, vaccination with influenza and pneumococcal vaccines together was effective in reducing the need for hospital admission for influenza and pneumonia. There was a strong indication that pneumococcal vaccination alone, was effective not only in the prevention of invasive pneumococcal disease, but also of pneumonia overall, although to a low degree.

Community-acquired pneumonia.

Community-acquired pneumonia (CAP) remains an important cause of morbidity and mortality. Streptococcus pneumoniae is the most common pathogen and respiratory syncitial virus the most important viral pathogen in children. The role of urinary antigen testing and PCR for the diagnosis forS. pneumoniae infection has been an important adjunct to clinical examination, showing good sensitivity and specificity. Host-related immune responses play an important role in defining the severity of illness. Other than the use of Activated Protein C and immunization, the clinical use of therapies designed to modulate these abnormal responses remains largely experimental. The 7-valent vaccine represents a major advance in the prevention of invasive pneumococcal disease. The importance of effective triage and the deleterious effects of deviation from protocols are underscored. Continuous positive pressure ventilation and noninvasive mechanical ventilation are available as options for respiratory support in cases of severe CAP and require further evaluation.

Pneumococcal vaccination: current and future issues.

Infection with Streptococcus pneumoniae remains a major global health burden meaning the development of effective vaccines is urgently needed. The current 23-valent polysaccharide vaccine has been shown to prevent pneumococcal pneumonia in immunocompetent young adults, but not in elderly persons. However, in prevention of invasive pneumococcal disease, the vaccine is efficacious in the elderly and may also be effective in some groups of immunocompromised patients. The polysaccharide vaccine is, therefore, recommended in all older (> or = 55-65 yrs of age) adults and in young children (>2 yrs of age) who have a high risk for pneumococcal disease. Revaccination can be safely performed and is recommended 5 yrs after the first dose. In children <2 yrs of age, the new polysaccharide-protein conjugate vaccines, including 7-11 serotypes, seem to be effective in the prevention of invasive disease, severe pneumonia and serotype-specific (and vaccine-related types) otitis media. The low serotype coverage, need for repeated doses, and high price, may decrease the usefulness of the new conjugates. However, the included serotypes correspond to those most often associated with penicillin resistance and vaccination is, therefore, a possible tool in limiting the spread of antibiotic-resistant pneumococci.

Pneumococcal Conjugate Vaccine

In February 2000, the new 7-valent pneumococcal polysaccharide-protein conjugate vaccine (PCV7) (Prevnar; Wyeth Lederle Vaccines, Pearl River, NY) was approved by the Food and Drug Administration (FDA) for the prevention of invasive pneumococcal disease (eg, meningitis and bacteremia) in infants and young children. This long-awaited event has received widespread applause from pediatric infectious disease experts who anticipate a dramatic decrease in these potentially fatal serious infections as the infants and young children who are at high risk become immunized. 1,2 The Centers for Disease Control and Prevention Advisory Committee on Immunization Practices (ACIP) recommends that the vaccine be given to all infants aged 2 to 23 months and to children aged 24 to 59 months who are at increased risk for pneumococcal disease, such as those who have sickle cell disease, human immunodeficiency disease virus infection, and other immunocompromising or chronic medical conditions.3 The ACIP also recommends that the vaccine be considered for all other children aged 24 to 59 months, with priority given to (1) those who are 24 to 35 months old; (2) those who are of Alaska Native, American Indian, or African American descent; and (3) those who attend group day care centers. Even though the vaccine has been demonstrated to be safe and effective in preventing invasive pneumococcal infections, the prevention of otitis media is another potential advantage. However, there is uncertainty among clinicians as to the impact this vaccine will have in preventing pneumococcal otitis media; thus, we otolaryngologists should be knowledgeable when we counsel parents and caregivers of infants and children who have acute otitis media (AOM) on what to realistically expect from the immunization.

Acute otitis media in the era of effective pneumococcal conjugate vaccine: will new pathogens emerge?

The immunogenicity of pneumococcal conjugate vaccine (PCV) in young infants and its serotype-specific efficacy in otitis media (OM) results in a modest reduction in total episodes of OM and a more substantial reduction in disease due to the most frequent pneumococcal serotypes. Since PCV will only prevent disease due to the most common serotypes, concerns about potential changes in the microbiology of OM have emerged. Insight into potential changes can be obtained from reviewing middle ear and nasopharyngeal isolates from studies of antimicrobial prophylaxis and bacterial polysaccharide immune globulin for prevention of OM and PCV for prevention of invasive pneumococcal disease, respectively. In children receiving PCV, a shift in serotypes of SP colonizing the nasopharynx has been observed. Since non-vaccine serotypes are already present in the community as the etiology of acute purulent OM, it is predictable that these non-vaccine serotypes will become more common especially in children less than two years of age.

Efficacy of pneumococcal conjugate vaccines in large scale field trials.

Each year Streptococcus pneumoniae causes approximately 1.2 million deaths worldwide from pneumonia. In the United States S. pneumoniae is estimated to cause 500,000 cases of pneumonia and 7 million episodes of acute otitis media annually. The current pneumococcal polysaccharide vaccine is ineffective in children <2 years old and may not produce an adequate antibody response until children reach the age of 5 years. Pneumococcal conjugate vaccines are immunogenic after primary and booster vaccination in young children and in children and adults with immunodeficiencies. Immunization with conjugate vaccines also induces a strong and rapid anamnestic response and enhanced functional activity of antibodies. Two large scale field trials of pneumococcal conjugate vaccines were initiated in 1995, 1 in California and 1 in Finland. The California trial, involving 37,868 children, evaluated the efficacy of a 7-valent conjugate for the prevention of invasive pneumococcal disease and secondarily evaluated its efficacy for acute otitis media and pneumonia. Preliminary results indicate 94% efficacy against invasive pneumococcal disease caused by serotypes included in the vaccine in fully or partially vaccinated children. Preliminary evidence from large scale field trials indicates that pneumococcal conjugate vaccines are effective in reducing invasive pneumococcal disease as well as acute otitis media and pneumonia in children and represents a significant advance in the prevention of childhood infectious diseases.

Fc gammaRIIa polymorphism in human immunodeficiency virus-infected children with invasive pneumococcal disease.

Invasive pneumococcal disease (IPD) occurs frequently in HIV-infected children and adults. Defects in complement function, opsonic capsular antibodies, and Fc receptor antibody-mediated phagocytosis could contribute to impaired host defense against Streptococcus pneumoniae. The objective of this study was to define the distribution of the three Fc gammaRIIa genotypes in HIV+ children, including those with IPD. Forty-eight HIV+ Hispanic children, including eight with IPD, followed at Bronx-Lebanon Hospital Center, Bronx, New York, nine HIV+ adults with IPD, and 56 HIV- Hispanic control subjects were studied. The children and adults were identified retrospectively except for one child who developed IPD during the study. Fc gammaRIIa genotypes were determined by PCR amplification of the Fc gammaRIIa locus from genomic DNA samples and hybridization of the PCR products with allele-specific oligonucleotides. Naturally occurring serum antibodies reactive with four pneumococcal polysaccharide serotypes were determined by ELISA in seven of eight children with IPD. There were no statistical differences in Fc gammaRIIa genotypes between HIV+ children with and without IPD, HIV+ adults with IPD, or HIV- Hispanics. The predominant IgG subclass of pneumococcal polysaccharide binding antibodies in the seven HIV+ children with IPD studied was IgG1. The distribution of Fc gammaRIIa genotypes in HIV+ children with and without IPD is similar to that of the normal Hispanic population. The prospect of passive immunotherapy with specific anticapsular antibodies might be a promising alternative for the treatment and/or prevention of IPD in HIV+ children and other immunodeficient groups.