Pertussis burden and acellular pertussis vaccine effectiveness in high risk children.

BACKGROUND: Pertussis hospitalisation is more common among infants born prematurely, who have significant comorbidities, or are Indigenous, but acellular pertussis (aP) vaccine effectiveness (VE) estimates in these sub-groups are lacking. We measured aP VE by Indigenous status, and policy-relevant categories of prematurity and comorbidity, in a population-based Australian cohort. METHODS: Perinatal, disease notification, hospitalisation, mortality, and vaccination data were linked to birth records in two Australian states (Western Australia and New South Wales) 2001-2012, with follow-up to the end of 2013. Children followed to 18 months of age were stratified by Aboriginality, prematurity (<32 vs 32-<37 weeks gestation) and comorbidities identified from hospital discharge coding. Rates, rate ratios and VE were calculated for first episode of hospitalised and non-hospitalised pertussis notifications using adjusted Cox proportional hazards models. RESULTS: Among >1,300,000 children, 63,867 (4·9%) were Aboriginal, 47,721 (3·6%) had at least one comorbidity and 3,771 first episodes of notified pertussis occurred <18 months of age; of these, 1,207 (32.0%) had an associated pertussis-coded hospitalisation. For hospitalised pertussis in Aboriginal and non-Aboriginal children, there was significant protection post dose 1 (VE 51% v 25%), 2 (VE 69% v 74%) and 3 (VE 76% v 80%). For children with co-morbidities, VE for hospitalised pertussis was low and non-significant post dose 1 (0%) and 2 (30%). Post dose 3, VE was significant for hospitalised pertussis (70%; 95% CI 29-87) but not for non-hospitalised pertussis (24%; 95% CI -49 to 61). CONCLUSIONS: For most Aboriginal and non-Aboriginal children, improved timeliness of current infant doses and higher antenatal coverage should further improve protection against pertussis of any severity. For children at highest risk of severe pertussis (born <32 weeks gestation or with significant medical comorbidities), our data suggest that additional measures-such as extra doses of pertussis-containing vaccines and/or vaccines with improved immunogenicity-are needed for protection.

Effectiveness of seasonal trivalent influenza vaccination against hospital-attended acute respiratory infections in pregnant women: A retrospective cohort study.

BACKGROUND: Pregnant women are at risk of serious influenza infection. Although previous studies indicate maternal influenza vaccination can prevent hospitalisation in young infants, there is limited evidence of the effect in mothers. METHODS: A cohort of 34,701 pregnant women delivering between 1 April 2012 and 31 December 2013 was created using birth records. Principal diagnosis codes from hospital emergency department (ED) and inpatient records were used to identify episodes of acute respiratory illness (ARI) during the 2012 and 2013 southern hemisphere influenza seasons. Cox regression models were used to calculate adjusted hazard ratios (aHRs) by maternal vaccination status, controlling for Indigenous status, socioeconomic level, medical conditions, and week of delivery. RESULTS: 3,007 (8.7%) women received a seasonal influenza vaccine during pregnancy. Vaccinated women were less likely to visit an ED during pregnancy for an ARI (9.7 visits per 10,000 person-days vs. 35.5 visits per 10,000 person-days; aHR: 0.19, 95% CI: 0.05-0.68). Vaccinated women were also less likely to be hospitalised with an ARI compared to unvaccinated women (16.2 hospitalisations per 10,000 person-days vs. 34.0 hospitalisations per 10,000 person-days; aHR: 0.35, 95% CI: 0.13-0.97). CONCLUSIONS: Influenza vaccination during pregnancy was associated with significantly fewer hospital attendances for ARI in pregnant women.

Detecting genotyping error using measures of degree of Hardy-Weinberg disequilibrium.

Tests for Hardy-Weinberg equilibrium (HWE) have been used to detect genotyping error, but those tests have low power unless the sample size is very large. We assessed the performance of measures of departure from HWE as an alternative way of screening for genotyping error. Three measures of the degree of disequilibrium (alpha, ,D, and F) were tested for their ability to detect genotyping error of 5% or more using simulations and a real dataset of 184 children with leukemia genotyped at 28 single nucleotide polymorphisms. The simulations indicate that all three disequilibrium coefficients can usefully detect genotyping error as judged by the area under the Receiver Operator Characteristic (ROC) curve. Their discriminative ability increases as the error rate increases, and is greater if the genotyping error is in the direction of the minor allele. Optimal thresholds for detecting genotyping error vary for different allele frequencies and patterns of genotyping error but allele frequency-specific thresholds can be nominated. Applying these thresholds would have picked up about 90% of genotyping errors in our actual dataset. Measures of departure from HWE may be useful for detecting genotyping error, but this needs to be confirmed in other real datasets.