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Objective: To assess the impact of a Hib vaccination booster campaign targeting children aged 6 months to 4 years between May and September 2003, following a nationwide increase in the number of invasive Haemophilus influenzae serotype b (Hib) cases in all age groups after 1999. Design: The Health Protection Agency Centre for Infections prospectively monitors all cases of H influenzae disease in England and Wales and collects data from primary care trusts (PCTs) on coverage for vaccines in the childhood programme. Population: Adults and children in England and Wales (January 1991 to December 2006) Results: Data on vaccine coverage during the Hib booster campaign were available for 288/303 (95%) PCTs in England and revealed coverage of 71.8% for the 6-12-month age group and 63.2% for the 13-48-month age group. The Hib booster campaign resulted in a dramatic reduction in cases within 12 months in the age groups targeted for the booster. This decline was followed by a reduction in the number of cases reported among older children and adults. Since the campaign, however, there has been an increase in the number of cases reported among 1-3-year-old children (13 cases in 2004, 26 cases in 2005 and 32 cases in 2006), primarily in children who were too young to be vaccinated in the booster campaign. This group of children will be targeted in the pre-school catch-up programme that began in September 2007. Conclusions: The Hib booster campaign has helped to re-establish herd immunity in the UK. The increase in Hib disease among toddlers after 2004 supports the decision to introduce routine boosting for Hib at 12 months of age. [ABSTRACT FROM AUTHOR]

A national seroprevalence study was performed to determine the prevalence of Haemophilus influenzae type b (Hib) antibodies in England and Wales in 2009, when Hib disease incidence was the lowest ever recorded. A total of 2,693 anonymised residual sera from routine diagnostic testing submitted by participating National Health Service hospital laboratories were tested for Hib anti-polyribosyl-ribitol phosphate (PRP) IgG antibodies using a fluorescent bead assay. Median anti-PRP IgG concentrations were highest in toddlers aged 1–4 years (2.65 μg/ml), followed by children aged 5–9 years (1.95 μg/ml). Antibody concentrations were significantly lower after this age, but were still significantly higher among 10–19 year-olds (0.54 μg/ml) compared with adults aged >20 years (0.16 μg/ ml; p<0.0001). Half of the adults (51%) did not have Hib antibody concentrations ≥0.15 μg/ml, the level considered to confer short-term protection. Thus, the current excellent Hib control appears to be the result of high anti-PRP antibody concentrations in children aged up to 10 years, achieved through the various childhood vaccination campaigns offering booster immunisation. The lack of seroprotection in adults emphasises the importance of maintaining control of the disease and, most probably carriage, in children, therefore raising the question as to whether long-term routine boosting of either pre-school children or adolescents may be required.

Objectives: To examine invasive pneumococcal disease (IPD) incidence, the impact of the 7-valent pneumococcal conjugate vaccines (PCV7s) programme on the distribution of Streptococcus pneumoniae serotypes and risk factors for IPD among HIV-positive adults., Methods: We analysed adults (aged ≥15 years) reported to the HIV and IPD national datasets in England and Wales (2000-2009). Through data-linkage, changes in IPD incidence and serotype distribution were examined. Risk factors for IPD among HIV-positive adults were assessed using a case-control study., Results: Among 63,109 HIV-positive adults, 951 were co-infected with IPD. The average annual incidence of IPD was 245 episodes per 100,000 HIV-positive adults and 246 of 100,000 among those aged 15-44 years. Incidence was higher among those not on antiretroviral therapy (ART) (281 of 100,000) and those with severe immunosuppression (563 of 100,000). Among 9283 adults aged 15-44 at IPD diagnosis, 2.4% were living with undiagnosed HIV. The proportion of IPD episodes in HIV-positive adults with serotypes covered by PCV7 was 23% in 2009, a 54% proportional reduction compared with pre-PCV7 (2000-2006); the reduction in adults of unknown HIV status was 70%. The proportion of IPD episodes among HIV-positive adults caused by serotypes covered by PCV13 was 61%. Significant risk factors for IPD in multivariate analysis included older aged (≥65 years), a lower nadir CD4 cell count and no previous ART., Conclusion: An HIV test should be offered and recommended to adults aged 15-44 years without other obvious IPD risk factors. Our study provides an evidence base to policy makers regarding the use of the new PCV13 in HIV-positive adults.

Objective: To describe the epidemiology of invasive pneumococcal disease (IPD) in England & Wales in the pre-conjugate vaccine era., Methods: We analysed reports of culture-confirmed IPD submitted to the national surveillance system between July 1996 and June 2006., Results: The incidence of IPD was 10 per 100,000 overall, and increased over time. The typical pattern of IPD by age was observed, with the highest incidence in young children and older adults. There was little change in IPD incidence in the elderly, despite the widespread use of 23-valent pneumococcal polysaccharide vaccines since 2003. The distribution of serotypes changed over time; notably the proportion of cases caused by serotype 14 decreased, and the proportion due to serotype 1 increased. The incidence of meningitis was 0.6 per 100,000 overall, and as a proportion of all IPD cases was most common in children under 1 year of age (30%). Particular serotypes were significantly associated with a presentation of meningitis, after controlling for age and year, and the case:carrier ratio varied markedly by serotype., Conclusions: This paper provides a baseline for evaluating the impact of 7-valent pneumococcal conjugate vaccines, introduced in September 2006. Ongoing high-quality laboratory-based surveillance of IPD in all age groups is essential., (2009 The British Infection Society. Published by Elsevier Ltd. All rights reserved.)

Streptococcus pneumoniae strains causing invasive pneumococcal disease (IPD) in the elderly population of England and Wales during the winter of 2003/2004 (1 November 2003 to 30 April 2004) were characterized by serotyping and genotyping in order to determine their population structure in the elderly. Serotyping and multilocus sequence typing (MLST) were carried out on 542 invasive isolates referred to the Respiratory and Systemic Infection Laboratory. Pneumococci were distributed among 32 serotypes and 144 MLST sequence types. A high genetic diversity was observed within the major serotypes. Genetic relatedness varied with regard to serotype. Isolates within serotypes 3, 7F and 8 were the most genetically related whereas serotypes 6A and 19F comprised isolates originating from unrelated ancestors. There was indirect evidence that some pneumococci were derived from clones that had undergone capsular switching in the past. Interestingly one case of IPD was caused by a pneumococcus originating from a clone that had undergone capsular switching from serotype 18C, a serotype included in 7-valent pneumococcal conjugate vaccine (PCV) to serotype 1 (serotype not included in PCV) suggesting that virulent clones with the potential ability to evade PCV existed in the pneumococcal population prior to the routine introduction of this vaccine. Isolates from 28 cases of apparent 23-valent pneumococcal polysaccharide vaccine (PPV) failure were included but there was no evidence of the emergence of particular clones associated with vaccine failures. Longitudinal studies based on serotypic and genetic characterization of pneumococci are fundamental to understanding the impact of both PPV and PCV on the genetic structure of pneumococcal populations.

A recent resurgence in serious infections due to Haemophilus influenzae type b (Hib) has been observed in the United Kingdom. More information on Hib transmission in the population is required in order to better understand the mechanism of this increase. The Public Health Laboratory Service (subsumed into the Health Protection Agency since April 2004) conducted four cross-sectional studies of asymptomatic oropharyngeal Hib carriage in children attending day-care nurseries in England and Wales in 1992, 1994, 1997 and 2002. These demonstrated a marked reduction in the prevalence of Hib colonization over time since vaccine introduction (3.98% in 1992; 0.70% in 1994; 0% in 1997; 0% in 2002), which did not explain the increase in invasive disease reports from 1999 onwards. We believe that a reduction in antibody levels over the first 5 years of life in immunized children in recent years has fuelled the rise in reported cases in the absence of an obvious increase in transmission.

The incidence of invasive Haemophilus influenzae type b (Hib) disease in the UK fell rapidly following the introduction of routine vaccination in 1992 and the implementation of a catch-up campaign in children under 4 years old in 1992-93. However, since 1999 the number of cases of Hib has been increasing, and in 2002 there were 134 cases in 0-4 year olds (266 in all ages). While still much less than the prevaccine burden of disease (over 800 cases a year in 0-4 year olds), this increase in incidence is worrying and has sparked a range of detailed investigations. In February 2003, the Department of Health announced a second catch-up campaign offering all children between 6 months and 4 years a further dose of Hib vaccine. The epidemiology of Hib disease in England and Wales between 1990 and 2002 is reviewed here to provide a context for this public health response.

A survey of invasive H. influenzae infections has been underway in six regions of England and Wales since September 1990. In the first year, there were 433 cases of which 362 (84%) were due to H. influenzae type b (Hib). The majority of Hib infections were in children aged less than 5 years; there being an annual incidence of 26.4/100,000 in this age group. Meningitis occurred in 56% of cases of Hib infection. The results confirm previous evidence of the need to incorporate Hib vaccination into the childhood immunisation schedule. The ongoing survey data will provide useful information to assess the impact of an Hib immunisation programme.