NSW immunisation performance: continuing progress but no room for complacency

Abstract

Aims: To describe trends in case notification data for vaccine-preventable diseases in NSW for 2010.Methods: Risk factor and vaccination status data were collected from cases through public health unit follow-up. Data from the NSW Notifiable Conditions Information Management System (NCIMS) were analysed by: local health district of residence; age; vaccination status; and sub-organism, where available. Results: Outbreaks of measles and pertussis were notified in 2010, associated with unimmunised groups (measles) or as a result of waning immunity (pertussis). Conclusion: With the exception of pertussis, most vaccine-preventable disease notifications remain low in NSW. Ensuring high levels of vaccination for travellers is important to prevent future outbreaks of vaccine-preventable disease, particularlymeasles. The objectives of vaccine-preventable disease surveillance are to: detect and investigate outbreaks of vaccinepreventable disease; identify contacts of patients who may be at risk of infection; identify cases of potential vaccine failure; and understand the epidemiology of vaccine-preventable disease to inform the development of prevention strategies. Notified cases of vaccinepreventable disease were defined according to national criteria. Under the NSW Public Health Act 1991, since 1991: medical practitioners have been required to notify patients diagnosed with measles and pertussis; laboratories have been required to notify patients diagnosed with measles, pertussis, rubella, Haemophilus influenzae serotype b invasive infection, meningococcal disease, mumps and rubella; and hospital general managers have been required to notify patients diagnosed with measles, pertussis,H. influenzae serotype b invasive infection, and meningococcal disease, to NSW Health (via public health units). Laboratories have also been required to notify patients with invasive pneumococcal infections since 2002. Notifications ofH. influenzae serotype b invasive infection, measles, meningococcal disease, pertussis, pneumococcal disease (people aged less than 5 years and 50years and over) and tetanus prompt public health follow-up according to NSW case definitions and response protocols. Notifications ofmumps and rubella are not routinely followed-up by public health units in NSW. Public health unit staff enter data gathered on notified cases into the statewide Notifiable Conditions Information Management System (NCIMS). This report describes notifications of vaccine-preventable diseases in New SouthWales (NSW) in 2010 and compares this with recent trends in surveillance data. Methods Notification data from theNSWNCIMSwere reviewed for cases of vaccine-preventable diseases with a date of onset in 2010. All rates were calculated using Australian Bureau of Statistics population estimates for the relevant year. Rates are presented as annual rates per 100 000 total population or population in age groups. Risk factor and vaccination status data were collected from notified cases through public health unit follow-up. In NSW, laboratories provide serotype data for measles, meningococcal and pneumococcal disease. Notified cases were analysed by place of usual residence according to geographical regions served by the relevant local health districts’ public health unit. Results Haemophilus influenzae serotype b invasive infection H. influenzae serotype b (Hib) is a bacillus which may form part of the flora of theupper respiratory tract. Thebacteria are spread through contact with droplets from the nose or throat of a person with the infection, usually in household-like settings. Infection can result in invasive disease including meningitis, epiglottitis, septic arthritis, cellulitis and pneumonia. Since 1993, vaccination against H. influenzae serotype b has been available and is provided for infants at 2, 4, 6 and 12 months of age. In 2006, theH. influenzae serotype b vaccine changed to PRP-T from PRP-OMP. Summary of notified cases In 2010, six cases of H. influenzae serotype b infection were notified which is similar to previous years. Two cases were children aged less than 1 year, two cases were children aged between 1–6 years, and two cases were adults aged 35 and 55 years. Three cases were male; no cases were notified in Aboriginal people in 2010. 10.1071/NB11028 Vol. 22(9–10) 2011 NSW Public Health Bulletin | 171 Vaccination status of cases Of the four cases of H. influenzae serotype b infection notified in children in 2010, one was unvaccinated and three were fully vaccinated for their age (an infant aged 7 months with three doses and two children aged 3 years with four doses). Comment H. influenzae serotype b is now rarely seen in NSW children.H. influenzae serotype b vaccination has successfully reduced the rate of disease incidence in unvaccinated populations. Measles Measles is an acute, highly infectious viral disease that can have serious complications. Prodromal symptoms of measles include fever, tiredness, cough, runny nose, sore red eyes and feeling unwell. A characteristic rash appears 3–7 days after the prodrome, beginning on the face and spreading down the body. The rash usually lasts 4–7 days. Summary of notified cases In 2010, 26 cases of measles were notified in NSW, compared to 19 in 2009. The highest notification rates were reported among young people aged at onset of their illness 10–14years (10cases, 2.2per100 000population) and15–19 years (seven cases, 1.5 per 100 000 population) (Figure 1). Eighteen cases (69%) were male; no cases were notified in Aboriginal people. Geographically, the highest notification rates were reported from the Northern NSW Local Health District (4.0 per 100 000 population) (Table 1). Vaccination status of cases Of the 26 cases, 18 (69%) were unvaccinated, two (8%) were vaccinated, two (8%) were partially vaccinated and four adult cases (15%) were unable to recall their vaccination status. Outbreaks Most cases of measles in NSW are notified either in nonimmune travellers who return with the infection from countries where measles is endemic, or in non-immune people who are exposed to a known case. Of the 26 cases notified in 2010, six (23%) were associated with overseas travel. Three of these cases resulted in further transmission affecting 20 people. One case who acquired the infection overseas was associated with transmission to one unvaccinated family member and one unvaccinated community contact. A second casewho acquired the infection overseas was associated with transmission to three unvaccinated family members and one airplane contact with uncertain vaccination history. A third overseas case, from the Northern NSW Local Health District, was associated with transmission in a high school (eight cases), a prison (four cases) and the community (two cases). Genotype There are different genotypes of themeasles virus. In 2010, eight cases had measles genotype information identified. Of these, one were identified as H1 (associated with travel to Vietnam), one was D8 (associated with travel to Sri Lanka), one was D4 (associated with travel to Italy), and five were D9 (one associated with travel to China, and four from the Northern NSW Local Health District cluster initially associated with travel to Malaysia). Comment People at risk of contracting measles are those who have never had measles or who have never been vaccinated. A second dose of measles-mumps-rubella (MMR) vaccine