Socioeconomic disadvantage and engagement with digital contact tracing for COVID-19 in Western Sydney: A secondary analysis of surveillance data.

OBJECTIVE: COVID-19 outcomes were highly inequitably distributed in Australia and worldwide. The digitalisation of public health interventions offers resource-efficiency and increased capacity for pandemic responses, but risks excluding the elderly and disadvantaged, reinforcing existing inequalities. Despite this, there has been little evaluation of the determinants of uptake of digital contact tracing. This paper describes the use of digital contact tracing for COVID-19 in a population in metropolitan Sydney and the determinants of engagement in this population. METHODS: Routinely collected surveillance data for residents of Western Sydney Local Health District, returning a positive SARS-CoV-2 result between 1st August 2021 and 12th February 2022, were extracted including responses to a digital contact tracing questionnaire. Individual records were linked to area-level socioeconomic indices of disadvantage. Descriptive analyses explored characteristics of non-responders and geospatial variation. Logistic regression was undertaken to evaluate the effect of age, sex and socioeconomic disadvantage on the odds of response. RESULTS: Of the 133 055 individuals included, 130 645 (98%) were issued a digital contact tracing questionnaire, and 106 432 (81%) responded. Odds of responding were lower in males (odds ratio: 0.79), individuals aged 80+ (odds ratio: 0.17) and the most disadvantaged communities (odds ratio: 0.32). CONCLUSIONS: Digital data collection for contact tracing was a scalable and efficient tool in the context of the Western Sydney Local Health District COVID-19 response. However, older people and individuals in disadvantaged communities were less likely to engage. IMPLICATIONS FOR PUBLIC HEALTH: Responses to future pandemics should leverage the resource-efficiency of digital interventions but should avoid compounding existing health inequalities.

The effectiveness of prophylaxis for measles contacts in NSW.

OBJECTIVES: As international estimates of the effectiveness of post-exposure prophylaxis of measles vary, we sought to determine the effectiveness of post-exposure prophylaxis with either vaccine or immunoglobulin in susceptible persons with known measles contact. METHODS: Data were obtained on all cases of measles notified in NSW between 1 March and 31 May 2006 and their contacts. The effectiveness of prophylaxis was calculated using the cohort method. RESULTS: During March to May 2006, 57 cases of measles were notified and 1760 measles contacts were identified, of which 553 were classified as susceptible. The calculated effectiveness of post-exposure prophylaxis with vaccine or immunoglobulin in preventing measles was 83.3% (95% CI: 27-96%). CONCLUSION: Post-exposure immunisation remains an effective tool for preventing secondary cases of measles.

Comparison of the validity and reliability of two image classification systems for the assessment of mammogram quality.

OBJECTIVE: To compare the reliability and validity of two classification systems used to evaluate the quality of mammograms: PGMI ('perfect', 'good', 'moderate' and 'inadequate') and EAR ('excellent', 'acceptable' and 'repeat'). SETTING: New South Wales (Australia) population-based mammography screening programme (BreastScreen NSW). METHODS: Thirty sets of mammograms were rated by 21 radiographers and an expert panel. PGMI and EAR criteria were used to assign ratings to the medio-lateral oblique (MLO) and cranio-caudal (CC) views for each set of films. Inter-observer reliability and criterion validity (compared with expert panel ratings) were assessed using mean weighted observed agreement and kappa statistics. RESULTS: Reliability: Kappa values for both classification systems were low (0.01-0.17). PGMI produced significantly higher values than EAR. Agreement between raters was higher using PGMI than EAR for the MLO view (77% versus 74%, P < 0.05), but was similar for the CC view. Dichotomized ratings ('acceptable' or 'needs repeating') did not improve reliability estimates. VALIDITY: Kappa values between raters and the reference standard were low for both classification systems (0.05-0.15). Agreement between raters and the reference standard was higher using PGMI than EAR for the MLO view (74% versus 63%), but was similar for the CC view. Dichotomized ratings of the MLO view showed slightly higher observer agreement. CONCLUSIONS: Both PGMI and EAR have poor reliability and validity in evaluating mammogram quality. EAR is not a suitable alternative to PGMI, which must be improved if it is to be useful.

Vaccine failures and vaccine effectiveness in children during measles outbreaks in New South Wales, March-May 2006.

During March to May 2006 the highest incidence of measles in New South Wales since 1998 provided an opportunity to estimate the effectiveness of the measles-mumps-rubella (MMR) vaccination program in preventing childhood measles, and describe any differences in clinical presentation between vaccinated and unvaccinated children. We reviewed records of all 33 notified cases of measles in children aged 1-14 years during a state-wide outbreak in New South Wales from March - May 2006. Six of the children had a confirmed history of vaccination with at least 1 dose of MMR. The children with previous vaccination tended to have milder disease than those without vaccination as judged by their reported number of symptoms and hospitalisation rates. The vaccinated children were less likely to have a typical measles rash. Two of the cases in previously vaccinated children may be due to secondary vaccine failure, although a lack of complete diagnostic testing limits our ability to confirm this. Vaccine effectiveness after receiving at least 1 dose of MMR is estimated to be 96% (95% CI 77.8-99%). MMR vaccination was effective in preventing measles in children during these outbreaks.

The natural history of vitamin D deficiency in African refugees living in Sydney.

OBJECTIVE: To describe the natural history of vitamin D deficiency in an at-risk population of African migrants living in Sydney. DESIGN, SETTING AND PARTICIPANTS: Opportunistic study of 25-hydroxyvitamin D [25(OH)D] concentrations over time in a community-based cohort of North African refugee families living in south-western Sydney. As part of a health-screening program, serum concentrations of 25(OH)D, parathyroid hormone (PTH), calcium, phosphate (PO(4)) and alkaline phosphatase (ALP) were measured in September 2006 (end of winter, T1). Results for 25(OH)D were made available, and treatment was recommended as appropriate. In February-March 2007 (end of summer, T2), in the setting of a separate study of high-dose vitamin D (stoss) therapy, the same cohort was contacted, and measurements were repeated. MAIN OUTCOME MEASURES: Changes in 25(OH)D, PTH, ALP and PO(4) concentrations between T1 and T2 in those who had not received vitamin D supplementation in the intervening period. RESULTS: We collected data from 149 participants at T1; by T2, 58 participants (39%) had been excluded or lost to follow-up. Data from 91 participants (46% female), all of whom had Type VI (very dark) skin pigmentation, were included in the analysis. All 91 were 25(OH)D deficient at T1. Between T1 and T2, mean 25(OH)D serum concentration increased from 19 nmol/L (SD, 5.6 nmol/L) to 36 nmol/L (SD, 12.4 nmol/L) (P < 0.001). Of the 91 participants, 79 (87%) remained vitamin D deficient at T2. Serum PTH and ALP activity decreased between T1 and T2 (P < 0.05). CONCLUSION: Despite a significant increase in 25(OH)D serum concentration over the study period, most participants (87%) remained 25(OH)D deficient at the end of summer. Our results support the current consensus that recommends annual screening for vitamin D deficiency and routine vitamin D supplementation in at-risk populations, such as dark-skinned or veiled groups.