The Impact of Prior Season Vaccination on Subsequent Influenza Vaccine Effectiveness to Prevent Influenza-related Hospitalizations Over 4 Influenza Seasons in Canada

BACKGROUND

Recent studies have demonstrated the possibility of negative associations between prior influenza vaccines and subsequent influenza vaccine effectiveness (VE), depending on season and strain. We investigated this association over 4 consecutive influenza seasons (2011-2012 through 2014-2015) in Canada.

METHODS

Using a matched test-negative design, laboratory-confirmed influenza cases and matched test-negative controls admitted to hospitals were enrolled. Patients were stratified into 4 groups according to influenza vaccine history (not vaccinated current and prior season [referent], vaccinated prior season only, vaccinated current season only, and vaccinated both current and prior season). Conditional logistic regression was used to estimate VE; prior vaccine impact was assessed each season for overall effect and effect stratified by age (<65 years, ≥65 years) and type/subtype (A/H1N1, A/H3N2, influenza B).

RESULTS

Overall, mainly nonsignificant associations were observed. Trends of nonsignificant decreased VE among patients repeatedly vaccinated in both prior and current season relative to the current season only were observed in the A/H3N2-dominant seasons of 2012-2013 and 2014-2015. Conversely, in 2011-2012, during which B viruses circulated, and in 2013-2014, when A/H1N1 circulated, being vaccinated in both seasons tended to result in a high VE in the current season against the dominant circulating subtype.

CONCLUSIONS

Prior vaccine impact on subsequent VE among Canadian inpatients was mainly nonsignificant. Even in circumstances where we observed a trend of negative impact, being repeatedly vaccinated was still more effective than not receiving the current season's vaccine. These findings favor continuation of annual influenza vaccination recommendations, particularly in older adults.

CLINICAL TRIALS REGISTRATION

NCT01517191.

Validation of the Seegene RV15 multiplex PCR for the detection of influenza A subtypes and influenza B lineages during national influenza surveillance in hospitalized adults

Background. The Serious Outcomes Surveillance Network of the Canadian Immunization Research Network (CIRN SOS) has been performing active influenza surveillance since 2009 (ClinicalTrials.gov identifier: NCT01517191). Influenza A and B viruses are identified and characterized using real-time reverse-transcriptase polymerase chain reaction (RT-PCR), and multiplex testing has been performed on a subset of patients to identify other respiratory virus aetiologies. Since both methods can identify influenza A and B, a direct comparison was performed.Methods. Validated real-time RT-PCRs from the World Health Organization (WHO) to identify influenza A and B viruses, characterize influenza A viruses into the H1N1 or H3N2 subtypes and describe influenza B viruses belonging to the Yamagata or Victoria lineages. In a subset of patients, the Seeplex RV15 One-Step ACE Detection assay (RV15) kit was also used for the detection of other respiratory viruses.Results. In total, 1111 nasopharyngeal swabs were tested by RV15 and real-time RT-PCRs for influenza A and B identification and characterization. For influenza A, RV15 showed 98.0 % sensitivity, 100 % specificity and 99.7 % accuracy. The performance characteristics of RV15 were similar for influenza A subtypes H1N1 and H3N2. For influenza B, RV15 had 99.2 % sensitivity, 100 % specificity and 99.8 % accuracy, with similar assay performance being shown for both the Yamagata and Victoria lineages.Conclusions. Overall, the detection of circulating subtypes of influenza A and lineages of influenza B by RV15 was similar to detection by real-time RT-PCR. Multiplex testing with RV15 allows for a more comprehensive respiratory virus surveillance in hospitalized adults, without significantly compromising the reliability of influenza A or B virus detection.

Point-of-care and point-of-'can': leveraging reference-laboratory capacity for integrated diagnosis of fever syndromes in the tropics

BACKGROUND

There is an urgent need for integrated diagnosis of febrile syndromes able to account for multiple pathogens and to inform decisions for clinical care and public health.

AIMS

To reflect on the evolving roles of laboratory-based testing for non-malarial febrile illnesses (NMFIs) in low-resource settings, and to consider how advances in diagnostics, in connectivity and transport, and in implementation of quality systems may substantially enhance the capacity of reference laboratories to bridge the current gap between remote passive surveillance and clinically meaningful integrated fever diagnosis.

SOURCES

Iterative search of PubMed databases, organizational reports, and expert consultation.

CONTENT

Implementation of new technologies-such as very broad molecular panels for surveillance and mass spectrometry-may considerably diminish capability gaps in reference laboratories in low-resource settings. Although the need for clinical bacteriology diagnostics is now recognized, the lack of new simple and rapid phenotypic tests for antimicrobial resistance remains a key deficiency. Several initiatives to strengthen diagnostic preparedness for infectious disease outbreaks have highlighted the need for functional tiered laboratory networks. Recently, dramatic headway in connectivity-such as combining automated readers with the image processing and data transmission capabilities of smartphones-now allows for more complex testing and interfacing with distant laboratory information systems while reducing workload and errors. Together with connectivity to transmit and receive results, new approaches to specimen collection and transport-such as the validation of rectal swabs and the use of aerial drones to transport specimens to distant laboratories-now make remote testing feasible. The above innovations also open up the possibility of implementing quality systems through community-level diagnostic stewardship. Finally, strengthened laboratory networks actively support the feasibility of implementing quality-assured point-of-care testing where it is needed.

IMPLICATIONS

Recent advances offer the present-day possibility of innovations to re-invent the relationship between distant reference laboratories and end-users for integrated diagnosis of NMFIs.

Interim estimates of 2013/14 influenza clinical severity and vaccine effectiveness in the prevention of laboratory-confirmed influenza-related hospitalisation, Canada, February 2014

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Helicobacter DNA in bile: correlation with hepato-biliary diseases

BACKGROUND

Helicobacter has been identified in isolated cases of hepato-biliary diseases, but its role in the pathogenesis of these conditions remains unclear.

AIM

To determine whether Helicobacter could be detected in bile obtained at endoscopic retrograde cholangiopancreatography, and to evaluate the prevalence of this infection in patients with hepato-biliary diseases.

METHODS

Bile was collected from 125 patients with various hepato-biliary diseases undergoing endoscopic retrograde cholangiopancreatography. Among them, 75 were diagnosed with biliary stones, 15 with pancreatico-biliary malignancies and four with primary sclerosing cholangitis. The detection of Helicobacter in DNA extracted from these bile samples was performed using Helicobacter genus-specific primers (capable of detecting 100-1000 organisms/mL).

RESULTS

Helicobacter was detected in all positive controls. Only three samples had polymerase chain reaction inhibitors. All remaining bile samples (122 patients with hepato-biliary diseases) were negative for Helicobacter DNA.

CONCLUSIONS

Helicobacter can be detected in bile samples using polymerase chain reaction. This infection, however, was not present in any of our patients diagnosed with gallstones or hepato-biliary malignancies, raising doubt as to the possible association between Helicobacter and these entities. Given the low sample size of patients with primary sclerosing cholangitis, more studies are required to determine whether an association exists with this condition.

Topical mupirocin for eradication of MRSA colonization with mupirocin-resistant strains

Topical mupirocin was able to interrupt colonization of 52% and 68% of methicillin-resistant Staphylococcus aureus (MRSA)-colonized patients carrying mupirocin-resistant and -sensitive strains, respectively, including 44.4% and 85.7% of those colonized only in the nares. Although a trend to decreased effectiveness was seen for clearing mupirocin-resistant MRSA, this agent can decolonize many patients with resistant strains.

Mycobacterium ulcerans infection (Buruli ulcer): first reported case in a traveler

A chronic, painless sore developed over a 2-month period on the left calf of a Canadian man traveling for 8 months in Africa. A presumptive diagnosis of a Mycobacterium spp. infection was made despite initially negative biopsy and culture results, after failure of several courses of anti-bacterial antibiotics. Mycobacterium ulcerans was eventually isolated and the lesion progressed despite treatment with multiple anti-mycobacterial agents. The lesion finally responded to wide and repeated excision, aggressive treatment with anti-mycobacterial antibiotics, and split-thickness skin grafting. The isolation and treatment of this unusual organism are discussed.

Ritanserin decreases portal pressure in conscious and unrestrained cirrhotic rats

We have recently demonstrated that ritanserin, a serotonin 5-hydroxytryptamine receptor antagonist void of systemic effects, caused a significant reduction of portal pressure in conscious cirrhotic dogs. The mechanism by which ritanserin lowers portal pressure is poorly defined. We investigated the splanchnic and systemic hemodynamic effects of ritanserin (0.63 mg/kg body wt i.v., a dose known to completely inhibit binding of 5-hydroxytryptamine to its receptors), in conscious and unrestrained cirrhotic rats (n = 13). Heparinized catheters were placed into the portal vein, inferior vena cava, aorta, and left ventricle with exit from the neck. Hemodynamic studies were performed 4 h after consciousness was regained. Cardiac output and regional blood flows were measured using radiolabeled microspheres and the reference sample method. Sixty minutes after administration, ritanserin caused a significant reduction of portal pressure (-17%) with minimal changes in portal venous inflow (+3%). Portal vascular resistance decreased significantly (-23%), whereas splanchnic arteriolar resistance was similar before and after ritanserin. A significant increase in mean arterial pressure (+5%) and cardiac output (+22%) was observed. Our results suggest that ritanserin lowers portal pressure through a mechanism separate from portal venous inflow. This effect could be due to changes in intrahepatic or on portocollateral resistances, or both. These findings support the potential use of this new agent in the treatment of portal hypertension.