Seven-valent Pneumococcal Conjugate Research Articles

Diphtheria Immunity in Australia: Should we be Concerned?

We report the results of the 2007 national serological survey of immunity to diphtheria in Australia to assess the impact of recent schedule changes on diphtheria immunity, and the adequacy of current policy in the context of increased international travel of people and pathogens. Residual sera (n =1656) collected opportunistically from Australian laboratories in 2007 were tested for diphtheria antibody levels using an enzyme immunoassay, with the protective threshold defined as ≥0.1 IU/mL. About 40% of adults aged ≥30 years are susceptible to diphtheria; following the removal of the 18-month booster and its replacement with a dose in adolescence offered through school-based dTpa vaccination program, 59% of children aged 3 years were susceptible to diphtheria, whilst adolescents demonstrated improved immunity. There is no apparent boosting of diphtheria immunity from meningococcal group C conjugate (MCC) or seven-valent pneumococcal conjugate (7vPCV) vaccines in relevant age groups. Australians who travel to diphtheria-endemic areas should be up-to-date with their vaccinations. Close monitoring of population immunity levels against diphtheria remains important to ensure that immunity does not decline to a level where wide-spread transmission would be possible.

Pneumococcal conjugate vaccination in persons with HIV: the effect of highly active antiretroviral therapy

Vaccination responses may be affected by concomitant use of highly active antiretroviral therapy (HAART). We aimed to determine HAART's impact on seven-valent pneumococcal conjugate (7vPnC) vaccine immunization with or without a Toll-like receptor 9 (TLR9) agonist adjuvant. Observational cohort study. Adults with HIV were immunized with double doses of 7vPnC +/-1 mg CPG 7909, a TLR9 agonist and vaccine adjuvant, at 0 and 3 months, and 23-valent pneumococcal polysaccharide vaccine at 9 months. We measured IgG levels (ELISA) and opsonophagocytic activity (OPA) at months 0, 3, 4, 9, and 10. Persistent 7vPnC vaccine responders were defined as individuals with two-fold IgG increases to 1 microg/ml or more for at least five of the 7vPnC serotypes at 9 months. We included 75 participants on HAART and 20 HAART-naive. Forty-one received CPG 7909 and 48 received placebo adjuvant. More persistent 7vPnC vaccine responders were found among HAART-treated than among HAART-naive (42.3 vs. 15.0%, P = 0.03). Mean loss of vaccine-specific IgG from month 4 to 9 was greater among HAART-naive than among HAART-treated (54.8 vs. 38.1%, P = 0.001). Functional activity (OPA) was higher among HAART-treated than among HAART-naive at 4, 9, and 10 months. In a logistic regression analysis (adjusted for baseline CD4 cell count, CPG 7909, smoking status, BMI, AIDS diagnosis, and age), HAART use was significantly associated with being persistent 7vPnC vaccine responder at month 9 [odds ratio = 4.65, 95% confidence interval (CI) 1.07-20.2]. HIV-infected adults on HAART achieved a more durable antibody response of higher functional activity following pneumococcal conjugate vaccination than HAART-naive individuals, independently of baseline CD4 cell count.

The Finnish decision-making process to recommend a new vaccine: From vaccine research to vaccination policy

This article takes a closer look at the decision-making process to recommend a new vaccine in the light of the Finnish experience. The criteria for evidence-based knowledge are examined in order to consider how public health decision-making in the area of immunisation evolves over time and from one context to the other on the basis of three of the more recent childhood vaccines (Haemophilus influenzae type b (Hib), seven-valent pneumococcal conjugate (PCV-7), and Human Papilloma Virus (HPV)). In the case of Hib vaccine, epidemiological research concerning both direct and indirect population protection was the driving force for implementation. By contrast, PCV-7 universal vaccination was not implemented on the basis of unfavourable cost-effectiveness evaluation. However, as this evaluation took place very early on, the cost-effectiveness analysis did not consider any indirect herd effects. Regarding the HPV vaccine, it is at present considered that cervical cancer will be better prevented by enhancing the already successful PAP smear screening programme. Surveillance and research are valuable tools for modern vaccine programme design. Market forces and advocacy groups strongly drive the development and implementation of new vaccines, meaning that impartial and evidence-based decision-making is essential to vaccine introduction into national programmes. At the same time, economic analyses are occupying an increasingly important place in this decision-making. Vaccine costs are not necessarily compared to government expenditure on illness and disease. From a moral point of view, it should not be forgotten that children ought to have the right to best available health.

Epidemiology of invasive Streptococcus pneumoniae infections in children in an area of Barcelona, Spain.

Streptococcus pneumoniae is the most common cause of bacteraemia, pneumonia, sinusitis and acute otitis media. With the advent of conjugate vaccines, there is now the possibility of preventing disease caused by this organism. However, little is known about the epidemiology of invasive pneumococcal disease in children in Spain. The aim of this study was to determine the incidence and the clinical and microbiologic characteristics of invasive pneumococcal disease in Sabadell, an industrial area in the province of Barcelona, Spain. From January 1990 to December 2000, the case records of children with pneumococcal invasive disease at Sabadell Hospital were retrospectively (1990-1996) reviewed and prospectively (1997-2000) collected. The hospital serves a population of 61,143 children under 15 y of age, 18,073 children under 4 y of age and 7300 children under 2 y of age. A total of 112 children (54% under 24 mo of age and 93% under 6 y of age) with invasive pneumococcal disease were diagnosed during a period of 11 y. The incidence of invasive pneumococcal disease was 76 per 100,000 for children aged 0 to 24 mo, 45 for children aged 0-48 mo and 16.6 for children aged 0-14 y. Occult bacteraemia was the most common manifestation of invasive pneumococcal disease (66 cases), pneumonia was the second form (34 cases) and meningitis (10 cases) and arthritis (2 cases) were the other clinical manifestations. Of the 105 strains tested, 8.6% were highly penicillin resistant, 37.1% were intermediately penicillin resistant. 16.2% were intermediately cefotaxime resistant and 32.4% were erythromycin resistant. Pneumococci of serogroups 6, 14, 18, 19, 1, 5, 4, 9, 23 and 33 were the most frequently isolated groups (92%) but only 6, 9, 14, 19 and 23 were resistant to penicillin, cefotaxime, or erythromycin. In this study the incidence of invasive pneumococcal disease was found to be greater than that reported elsewhere in Spain and Europe. Penicillin resistance levels are high but the trend towards increasing penicillin resistance may have ended over the past few years. The currently licensed seven-valent (7-V) pneumococcal conjugate vaccine would cover 78% of cases of invasive pneumococcal in children aged 0-14 y, 80% in children aged 0-24 mo and 100% of cases of penicillin- or cefotaxime-resistant invasive pneumococcal disease.