Diagnostic testing in influenza and pertussis related paediatric intensive care unit admissions,Queensland, Australia, 1997-2013.

Severe respiratory infections make up a large proportion of Australian paediatric intensive care unit (ICU) admissions each year. Identification of the causative pathogen is important and informs clinical management. We investigated the use of polymerase chain reaction (PCR) in the ICU-setting using data collated by the Australian and New Zealand Paediatric Intensive Care (ANZPIC) Registry from five ICUs in Queensland, Australia. We describe diagnostic testing use among pertussis and influenza-related paediatric ICU admissions between 01 January 1997 and 31 December 2013.

Sevenfold rise in likelihood of pertussis test requests in a stable set of Australian general practice encounters, 2000-2011.

OBJECTIVE: To better understand the role that diagnostic test-ordering behaviour of general practitioners has on current pertussis epidemiology in Australia. DESIGN AND SETTING: Analysis of Australian general practice encounter data (from the Bettering the Evaluation and Care of Health [BEACH] program) on 13 "pertussis-related problem" (PRP) codes that were most likely to result in a pertussis laboratory test request and Australian pertussis notifications data (from the National Notifiable Diseases Surveillance System [NNDSS]) for the period April 2000 to March 2011. MAIN OUTCOME MEASURES: The change in the proportion of PRP general practice encounters with a pertussis test request between 2000 and 2011, and the change in national pertussis notifications over the same period. RESULTS: The proportion of PRP encounters resulting in a pertussis test request increased from 0.25% between April 2000 and March 2004 to 1.71% between April 2010 and March 2011 (odds ratio, 7.0; 95% CI, 5.5-8.8). The BEACH data on pertussis testing and NNDSS data on pertussis notifications were highly correlated (r = 0.99), and the notification data mirrored the likelihood of a pertussis test request in general practice. The proportion of NNDSS pertussis notifications with a polymerase chain reaction (PCR)-confirmed diagnosis increased from 16.3% between April 2000 and March 2004 to 65.3% between April 2010 and March 2011. CONCLUSION: An increase in pertussis testing following recognition of early epidemic cases may have led to identification of previously undetected infections, resulting in a further increase in notified disease and awareness among GPs. The changing likelihood of being tested may also be due to expanding availability and use of PCR testing in Australia.

Effectiveness of parental cocooning as a vaccination strategy to prevent pertussis infection in infants: A case-control study.

BACKGROUND: During a pertussis epidemic in 2009, the Department of Health, Victoria, Australia, implemented a cocoon program offering parents of new babies a funded-dose of pertussis-containing vaccine. We assessed vaccine effectiveness (VE) of the program in reducing pertussis infection in infants. METHODS: Using a matched case-control design, infants aged <12 months that were notified with pertussis between 1 January 2010 and 31 December 2011, and born during the time that the cocoon program was in place, were identified. Controls were matched by area of residence and date of birth. Telephone interviews we conducted to ascertain parents' vaccination status, and if vaccinated, timing of vaccination receipt relative to the birth of their baby. Odds ratios (ORs) were calculated for the association between vaccination and pertussis infection, with VE calculated as (1 - OR) × 100%. RESULTS: The study recruited 215 cases and 240 controls (response rates 67% and 25% of eligible participants, respectively). Vaccination of both parents after delivery of the infant and ≥28 days prior to illness onset reduced pertussis infection by 77% (Vaccine Effectiveness [VE] = 77% (confidence interval [95% CI], 18-93%). After adjusting for maternal education, presence of a sibling within the household, and the infants' primary course vaccination status, the adjusted VE was 64% (95% CI, -58-92%). CONCLUSIONS: Although not reaching statistical significance, our results demonstrated that cocoon immunisation - where both parents are vaccinated in the post-partum period - may offer some protection again infant pertussis infection. Cocoon immunisation could be considered in circumstances where antenatal vaccination of the mother has not occurred.

Epidemiology of pertussis-related paediatric intensive care unit (ICU) admissions in Australia, 1997-2013: an observational study.

OBJECTIVE: To review the epidemiology of pertussis-related intensive care unit (ICU) admissions across Australia, over a 17-year period. DESIGN: Retrospective descriptive study. SETTING: Australian ICUs contributing data to the Australian and New Zealand Paediatric Intensive Care (ANZPIC) Registry. The number of contributing ICUs increased over the study period, from 8 specialist paediatric ICUs in 1997 to 8 specialist paediatric and 13 general ICUs in 2013. PARTICIPANTS: All paediatric (<16 years) ICU admissions, coded as pertussis-related, between 1 January 1997 and 31 December 2013. RESULTS: A total of 373 pertussis-coded ICU admissions were identified in the ANZPIC Registry over the study period. Of these cases, 52.8% occurred during the 4 years of the recent Australian epidemic (2009-2012). ICU admissions were most likely to occur in infants aged younger than 6 weeks (41.8%, n=156) and aged 6 weeks to 4 months (42.9%, n=160). The median length of stay for pertussis-related ICU admissions was 3.6 days, with 77.5% of cases staying in ICU for <7 days. Approximately half of all admissions (54.8%) required some form of respiratory support, with 32.7% requiring invasive respiratory support. Over the study period, 23 deaths were recorded (6.2% of pertussis-related ICU admissions), of which 20 (87.0%) were infants <4 months old. CONCLUSIONS: Pertussis-related ICU admissions occur primarily in infants too young to be fully protected from active immunisation. More needs to be done to protect these high-risk infants, such as maternal immunisation.

Epidemiology of Australian Influenza-Related Paediatric Intensive Care Unit Admissions, 1997-2013.

BACKGROUND: Influenza virus predictably causes an annual epidemic resulting in a considerable burden of illness in Australia. Children are disproportionately affected and can experience severe illness and complications, which occasionally result in death. METHODS: We conducted a retrospective descriptive study using data collated in the Australian and New Zealand Paediatric Intensive Care (ANZPIC) Registry of influenza-related intensive care unit (ICU) admissions over a 17-year period (1997-2013, inclusive) in children <16 years old. National laboratory-confirmed influenza notifications were used for comparison. RESULTS: Between 1997 and 2013, a total of 704 influenza-related ICU admissions were recorded, at a rate of 6.2 per 1,000 all-cause ICU admissions. Age at admission ranged from 0 days and 15.9 years (median = 2.1 years), with 135 (19.2%) aged <6 months. Pneumonia/pneumonitis and bronchiolitis were the most common primary diagnoses among influenza-related admissions (21.9% and 13.6%, respectively). More than half of total cases (59.2%) were previously healthy (no co-morbidities recorded), and in the remainder, chronic lung disease (16.7%) and asthma (12.5%) were the most common co-morbidities recorded. Pathogen co-detection occurred in 24.7% of cases, most commonly with respiratory syncytial virus or a staphylococcal species. Median length of all ICU admissions was 3.2 days (range 2.0 hours- 107.4 days) and 361 (51.3%) admissions required invasive respiratory support for a median duration of 4.3 days (range 0.2 hours- 107.5 days). There were 27 deaths recorded, 14 (51.9%) in children without a recorded co-morbidity. CONCLUSION: Influenza causes a substantial number of ICU admissions in Australian children each year with the majority occurring in previously healthy children.

Pertussis Seasonality Evident in Polymerase Chain Reaction and Serological Testing Data, Queensland, Australia.

We investigated the seasonality of pertussis in Queensland, Australia, between 2008 and 2011 using notification and laboratory data. Polymerase chain reaction and serology testing data demonstrate that in the vaccine era, pertussis remains a seasonal illness, with annual peaks in summer months, and that the seasonality of notification data is masked by testing trends.

The risk of fever following one dose of trivalent inactivated influenza vaccine in children aged ≥6 months to <36 months: a comparison of published and unpublished studies.

There are limited summary data published on the risk of fever and febrile seizures in children following influenza vaccination. We performed a review of the risk of fever and febrile seizures following receipt of trivalent inactivated influenza vaccine (TIV) in children aged ≥6 months to <36 months, searching PubMED and Google Scholar for English language articles from 2000 onwards, and initiated or ongoing unpublished studies since September 2007 using Clinicaltrials.gov. Exclusions included other vaccine co-administration, missing ages or participant numbers, or unmeasured fever. We reviewed articles and collated results using a standard data extraction template. We identified a total of 909 published papers and unpublished trials from a search conducted on 23 January 2013, 669 from Google Scholar, 114 from PubMed and 126 from the Clinicaltrials.gov online database. After excluding 890 published papers or unpublished trials, 5 published papers and 14 unpublished trials were included in this review. Extracted data on number of events, children at risk and time of follow-up were converted to the risk of fever, which was averaged per week of follow-up (referred to as 'averaged weekly risk'). Following one dose of TIV, the median averaged weekly risk of any fever (≥37.5°C) was 26.0% (range 10.3-70.0%) in unpublished trials compared to 8.2% (range 5.3-28.3%) in published papers (p=0.04). The median averaged weekly risk of severe fever (≥39.0°C) was 3.2% (range 0-10.0%) and 2.0% (range 0.6-17.0%), respectively (p=0.91). Variation in the reporting of fever by participant age groups, time since vaccination and the definition or measurement of fever resulted in a wide range of risk estimates. Reporting of febrile reactions should be standardised to allow comparison between manufacturers and influenza seasons.