The ongoing value of first few X studies for COVID-19 in the Western Pacific Region

First few ‘X’ (FFX) studies for COVID-19 involve data collection from confirmed cases and their close contacts. They remain relevant especially as many remain susceptible to infection, and as they can provide detailed insight into vaccine effectiveness and the epidemiology of variants of concern, helping to inform a proportionate health response

Description of social contacts among student cases of pandemic influenza during the containment phase, Melbourne, Australia, 2009

Introduction: Students comprised the majority of early cases of influenza A(H1N1)pdm09 in Melbourne, Australia. Students and school settings were targeted for public health interventions following the emergence of pH1N1. This study was conducted to describe changes in social contacts among the earliest confirmed student cases of pH1N1 in Melbourne, Australia, to inform future pandemic control policy and explore transmission model assumptions. Methods: A retrospective cross-sectional behavioural study of student cases with laboratory-confirmed pH1N1 between 28 April and 3 June 2009 was conducted in 2009. Demographics, symptom onset dates and detailed information on regular and additional extracurricular activities were collected. Summary measures for activities were calculated, including median group size and median number of close contacts and attendance during the students' exposure and infectious periods or during school closures. A multivariable model was used to assess associations between rates of participation in extracurricular activities and both school closures and students' infectious periods. Results: Among 162 eligible cases, 99 students participated. Students reported social contact in both curricular and extra-curricular activities. Group size and total number of close contacts varied. While participation in activities decreased during the students' infectious periods and during school closures, social contact was common during periods when isolation was advised and during school closures. Discussion: This study demonstrates the potential central role of young people in pandemic disease transmission given the level of non-adherence to prevention and control measures. These finding have public health implications for both informing modelling estimates of future pandemics and targeting prevention and control strategies to young people

The spread of influenza A(H1N1)pdm09 in Victorian school children in 2009:iImplications for revised pandemic planning

Background Victoria was the first state in Australia to experience community transmission of influenza A(H1N1)pdm09. We undertook a descriptive epidemiological analysis of the first 1,000 notified cases to describe the epidemic associated with school children and explore implications for school closure and antiviral distribution policy in revised pandemic plans. Methods Records of the first 1,000 laboratory-confirmed cases of influenza A(H1N1)pdm09 notified to the Victorian Government Department of Health between 20 May and 5 June 2009 were extracted from the state’s notifiable infectious diseases database. Descriptive analyses were conducted on case demographics, symptoms, case treatment, prophylaxis of contacts and distribution of cases in schools. Results Two-thirds of the first 1,000 cases were school-aged (5–17 years) with cases in 203 schools, particularly along the north and western peripheries of the metropolitan area. Cases in one school accounted for nearly 8% of all cases but the school was not closed until nine days after symptom onset of the first identified case. Amongst all cases, cough (85%) was the most commonly reported symptom followed by fever (68%) although this was significantly higher in primary school children (76%). The risk of hospitalisation was 2%. The median time between illness onset and notification of laboratory confirmation was four days, with only 10% of cases notified within two days of onset and thus eligible for oseltamivir treatment. Nearly 6,000 contacts were followed up for prophylaxis. Conclusions With a generally mild clinical course and widespread transmission before its detection, limited and short-term school closures appeared to have minimal impact on influenza A(H1N1)pdm09 transmission. Antiviral treatment could rarely be delivered to cases within 48 hours of symptom onset. These scenarios and lessons learned from them need to be incorporated into revisions of pandemic plans

Evolution of seroprevalence to SARS-CoV-2 in blood donors in Sarajevo Canton, Federation of Bosnia and Herzegovina: Cross-sectional and longitudinal studies

Background: Sarajevo Canton in the Federation of Bosnia and Herzegovina has recorded several waves of high SARS-CoV-2 transmission and has struggled to reach adequate vaccination coverage. We describe the evolution of infection- and vaccine- induced SARS-CoV-2 antibody response and persistence. Methods: We conducted repeated cross-sectional analyses of blood donors aged 18–65 years in Sarajevo Canton in November–December 2020 and 2021. We ana- lyzed serum samples for anti-nucleocapsid (anti-N) and anti-spike (anti-S) antibodies. To assess immune durability, we conducted longitudinal analyses of seropositive participants at 6 and 12 months. Results: One thousand fifteen participants were included in Phase 1 (November– December 2020) and 1152 in Phase 2 (November–December 2021). Seropreva- lence increased significantly from 19.2% (95% CI: 17.2%–21.4%) in Phase 1 to 91.6% (95% CI: 89.8%–93.1%) in Phase 2. Anti-S IgG titers were significantly higher among vaccinated (58.5%) than unvaccinated infected participants across vaccine products (p < 0.001), though highest among those who received an mRNA vaccine. At 6 months, 78/82 (95.1%) participants maintained anti-spike seroposi- tivity; at 12 months, 58/58 (100.0%) participants were seropositive, and 33 (56.9%) had completed the primary vaccine series within 6 months. Among 11 unvaccinated participants who were not re-infected at 12 months, anti-S IgG declined from median 770.1 (IQR 615.0–1321.7) to 290.8 (IQR 175.7–400.3). Anti-N IgG antibodies waned earlier, from 35.4% seropositive at 6 months to 24.1% at 12 months

Intrahousehold Transmission of Pandemic (H1N1) 2009 Virus, Victoria, Australia

TOC Summary: Antiviral prophylaxis for quarantined contacts reduces secondary transmission

Australian general practitioner chlamydia testing rates among young people

Objective:\ud To describe the proportion of 16–29-year-olds tested for chlamydia by Australian general practitioners in a 12-month period.\ud \ud Design and setting:\ud Between October 2007 and September 2008, the national chlamydia testing rate in 16–29-year-olds was calculated by dividing the number of Medicare-reimbursed chlamydia tests by two denominators: (i) Medicare-reimbursed GP consultations; and (ii) estimated resident populations adjusted for the proportion who were sexually active.\ud \ud Main outcome measures:\ud GP chlamydia testing rates in 16–29-year-olds per 100 patients attending a GP consultation and per 100 sexually active population, by patient age and sex, state/territory of residence, and remoteness area.\ud \ud Results:\ud Among the estimated Australian population of 16–29-year-olds, 85.6% of females and 64.4% of males had at least one GP consultation in the 12-month period. The national GP chlamydia testing rate per 100 patients was 8.9% (95% CI, 8.88%–8.94%). The national GP chlamydia testing rate per 100 sexually active population was 8.0% (95% CI, 7.92%–7.98%). The rate per 100 sexually active population was higher in females (12.5%) compared with males (3.7%) (P < 0.01); higher in 20–24-year-olds (9.0%) compared with 16–19-year-olds (8.7%) and 25–29-year-olds (6.6%) (P < 0.01); higher in those living in non-metropolitan areas (11.0%) compared with metropolitan areas (8.4%) (P < 0.01); and highest in those living in the Northern Territory (21.4%) compared with other jurisdictions (P < 0.01).\ud \ud Conclusions:\ud Despite clinical guidelines recommending annual chlamydia testing for sexually active 15–29-year-olds, our analysis showed that a high proportion of young people aged 16–29 years attend a GP each year, but few of the sexually active population in this age group were tested for chlamydia in general practice. Strategies are needed to support GPs to enhance chlamydia testing in young people

The spread of influenza A(H1N1)pdm09 in Victorian school children in 2009: implications for revised pandemic planning

Background: Victoria was the first state in Australia to experience community transmission of influenza A(H1N1)pdm09. We undertook a descriptive epidemiological analysis of the first 1,000 notified cases to describe the epidemic associated with school children and explore implications for school closure and antiviral distribution policy in revised pandemic plans.\ud \ud Methods: Records of the first 1,000 laboratory-confirmed cases of influenza A(H1N1)pdm09 notified to the Victorian Government Department of Health between 20 May and 5 June 2009 were extracted from the state's notifiable infectious diseases database. Descriptive analyses were conducted on case demographics, symptoms, case treatment, prophylaxis of contacts and distribution of cases in schools.\ud \ud Results: Two-thirds of the first 1,000 cases were school-aged (5–17 years) with cases in 203 schools, particularly along the north and western peripheries of the metropolitan area. Cases in one school accounted for nearly 8% of all cases but the school was not closed until nine days after symptom onset of the first identified case. Amongst all cases, cough (85%) was the most commonly reported symptom followed by fever (68%) although this was significantly higher in primary school children (76%). The risk of hospitalisation was 2%. The median time between illness onset and notification of laboratory confirmation was four days, with only 10% of cases notified within two days of onset and thus eligible for oseltamivir treatment. Nearly 6,000 contacts were followed up for prophylaxis.\ud \ud Conclusions: With a generally mild clinical course and widespread transmission before its detection, limited and short-term school closures appeared to have minimal impact on influenza A(H1N1)pdm09 transmission. Antiviral treatment could rarely be delivered to cases within 48 hours of symptom onset. These scenarios and lessons learned from them need to be incorporated into revisions of pandemic plans

A new national Chlamydia Sentinel Surveillance System in Australia: evaluation of the first stage of implementation

The Australian Collaboration for Chlamydia Enhanced Sentinel Surveillance (ACCESS) was established with funding from the Department of Health and Ageing to trial the monitoring of the uptake and outcome of chlamydia testing in Australia. ACCESS involved 6 separate networks; 5 clinical networks involving sexual health services, family planning clinics, general practices, antenatal clinics, Aboriginal community controlled health services, and 1 laboratory network. The program ran from May 2007 to September 2010. An evaluation of ACCESS was undertaken in early 2010, 2 years after the program was funded. At the time of the evaluation, 76 of the 91 participating sites were contributing data. The jurisdictional distribution of the 76 sites generally matched the jurisdictional distribution of the Australian population. In 2008, the chlamydia testing rates in persons aged 16-29 years attending the 26 general practices was 4.2% in males and 7.0% in females. At the 25 sexual health services, the chlamydia testing rates in heterosexuals aged less than 25 years in 2008 was 77% in males and 74% in females. Between 2004 and 2008, the chlamydia positivity rate increased significantly in heterosexual females aged less than 25 years attending the sexual health services, from 11.5% to 14.1% (P < 0.01). Data completeness was above 85% for all core variables except Aboriginal and/or Torres Strait Islander status and country of birth, which ranged from 68%-100%, and 74%-100%, respectively, per network. There were delays in establishment of the system due to recruitment of 91 sites, multiple ethics applications and establishment of automated extraction programs in 10 different database systems, to transform clinic records into a common, pre-defined surveillance format. ACCESS has considerable potential as a mechanism toward supporting a better understanding of long-term trends in chlamydia notifications and to support policy and program delivery