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Volume 7 No 4; 25 January 2013

HPA study aims to better assess meningococcal disease burden and inform vaccination policy

A unique “proof of concept” study, funded jointly by the Meningitis Research Foundation and Meningitis UK, is currently under way and aims to provide a cost-effective approach to linking epidemiological, clinical, microbiological and outcome data on Invasive Meningococcal Disease (IMD) in England through use of multiple national datasets. Due to be completed during the coming year, the study is being conducted by the HPA Immunisation, Hepatitis and Blood Safety Department (IHBSD) in collaboration with the Agency’s Meningococcal Reference Unit (MRU) [1,2]. By developing a standardised methodology for routine linkage of national datasets, it is hoped that this innovative project will provide a model for other public health surveillance programmes for vaccine-preventable infections.

IMD is caused by the bacterium, Neisseria meningitidis, which can be characterised into different groups depending on the properties of their outer sugar (polysaccharide) capsule. Five capsular groups (A, B, C, W and Y), however, are responsible for almost all IMD, although group C disease has now been virtually eliminated in the UK through routine vaccination that was introduced in 1999. Other capsular groups, especially group B which is currently responsible for >85% of all IMD cases, continue to cause serious infections such as meningitis and septicaemia, usually in healthy individuals. Although IMD occurs in all ages, the highest incidence is in children under 5 years of age and, to a lesser extent, adolescents. Around 5% of IMD cases are fatal and a significant proportion of survivors will develop long-term complications. Those with meningococcal septicaemia may, for example, require limb amputations while those with meningococcal meningitis may develop epilepsy, hearing loss, cerebral palsy, learning difficulties or behavioural problems.

The HPA MRU receives isolates and clinical samples from hospital laboratories throughout England, Wales and Northern Ireland. Although referral is very complete, the total number of IMD cases in England is higher because some cases of clinically diagnosed IMD are never confirmed, perhaps because the patient had already received antibiotics before samples were taken. In addition, some laboratories undertake their own testing and/or fail to refer samples from positive cases to the HPA MRU.

In order to better estimate the total burden of IMD in England, the HPA will attempt to link a number of different national data sources – including hospital admissions, electronic laboratory reports and death registrations – to collect more detailed clinical information about the laboratory-confirmed cases, their stay in hospital, any serious complications and whether they survived their infection. This is of particular importance for some of the less common capsular groups which can cause serious illness with a more varied clinical presentation. Capsular groups W and Y, for example, can cause meningococcal pneumonia in older adults who often have significant underlying co-morbidities and are more likely to die of their infection.

The collection of clinical data onlaboratory-confirmed cases will also allow linkage with detailed molecular and other typing data collected by the HPA MRU. Such information could play a vital role in identifying key components within the bacteria that may important for causing serious infections in humans and could form potential targets for future vaccines. The information collected as part of this project will also facilitate modelling of the potential impact (including cost-effectiveness) of new vaccines which, in turn, can be used to inform national vaccination policy. In addition to two conjugate vaccines against meningococcal groups A, C, W and Y, a broad-spectrum protein-based meningococcal vaccine (4CMenB, Bexsero™, Novartis) has recently received its marketing licence from the European Medicines Agency. Bexsero™ is the first vaccine licensed to protect against MenB in all age groups, including infants as young as two months of age. The information collected as part of the linkage project could play an important role in decisions relating to the introduction of these vaccines into the national immunisation programme.

References

1. HPA MRU provides a national service for meningococcal species confirmation and sero-/geno-grouping of invasive clinical isolates as well as a free national polymerase chain reaction (PCR) service for detecting meningococcal DNA in clinical specimens.

2. The study began in January 2013 and is due to be completed during 2013. For further information please contact the Dr Shamez Ladhani, the lead investigator, email: shamez.ladhani@hpa.org.uk.

3. For more information about Meningitis UK and Meningitis Research Foundation, and the research they fund, see: www.meningitisuk.org and www.meningitis.org.

Revised ACDP guidance on decontamination of endoscopes

Advisory Committee on Dangerous Pathogens (ACDP) guidance on endoscopy decontamination for TSE infection control has been revised.

Previously, guidance advised that endoscopes used for invasive procedures on patients at risk of variant CJD should be removed from general use (and quarantined or destroyed). This affected procedures carried out on individuals notified of an increased risk of vCJD, including a cohort of individuals treated with UK sourced plasma products in the 1980s and 90s.

The updated guidance now allows such endoscopes to go back into general use (in most cases) provided they have been decontaminated according to national guidelines [1].

Reference

1. DH. Guidance from the ACDP TSE Risk Management Subgroup (formerly TSE Working Group), January 2013 update: http://www.dh.gov.uk/health/2012/11/acdp-guidance/.