Publications by authors named "Bjørn G Iversen"

10 Publications

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Counting pandemic deaths: comparing reported numbers of deaths from influenza A(H1N1)pdm09 with estimated excess mortality.

Influenza Other Respir Viruses 2013 Nov 8;7(6):1370-9. Epub 2013 Jun 8.

Department of Infectious Disease Epidemiology, Norwegian Institute of Public Health, Oslo, Norway; Department of Biostatistics, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.

Background: During the wave 1 of the influenza A(H1N1)pdm09 virus, Norway appeared to be suffering from high mortality rates. However, by the end of the pandemic, it was widely reported that the number of deaths were much lower than previous years.

Objectives: The mortality burden from influenza is often assessed by two different approaches: counting influenza-certified deaths and estimating the mortality burden using models. The purpose of this study is to compare the number of reported deaths with results from two different models for estimating excess mortality during the pandemic in Norway. Additionally, mortality estimates for the pandemic season are compared with non-pandemic influenza seasons.

Methods: Numbers on reported influenza A(N1h1)pdm09 deaths are gived by the Cause of Death Registry at Statistics Norway and an ad hoc registry at the Norwegian Institute of Public Health. Overall and Pnemumonia and Influenza certified mortality is modeled using Poission regression, adjusting for levels of reported influenza-like illness and seasonal and year-to-year variation.

Results And Conclusions: Modelling results suggest that the excess mortality in older age groups is considerably lower during the pandemic than non-pandemic seasons, but there are indications of an excess beyond what was reported during the pandemic. This highlights the benefits of both methods and the importance of explaining where these numbers come from.
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http://dx.doi.org/10.1111/irv.12125DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4634244PMC
November 2013

Effect of vaccines and antivirals during the major 2009 A(H1N1) pandemic wave in Norway--and the influence of vaccination timing.

PLoS One 2012 10;7(1):e30018. Epub 2012 Jan 10.

Department of Biostatistics, Institute of Basic Medical Science, University of Oslo, Oslo, Norway.

To evaluate the impact of mass vaccination with adjuvanted vaccines (eventually 40% population coverage) and antivirals during the 2009 influenza pandemic in Norway, we fitted an age-structured SEIR model using data on vaccinations and sales of antivirals in 2009/10 in Norway to Norwegian ILI surveillance data from 5 October 2009 to 4 January 2010. We estimate a clinical attack rate of approximately 30% (28.7-29.8%), with highest disease rates among children 0-14 years (43-44%). Vaccination started in week 43 and came too late to have a strong influence on the pandemic in Norway. Our results indicate that the countermeasures prevented approximately 11-12% of potential cases relative to an unmitigated pandemic. Vaccination was found responsible for roughly 3 in 4 of the avoided infections. An estimated 50% reduction in the clinical attack rate would have resulted from vaccination alone, had the campaign started 6 weeks earlier. Had vaccination been prioritized for children first, the intervention should have commenced approximately 5 weeks earlier in order to achieve the same 50% reduction. In comparison, we estimate that a non-adjuvanted vaccination program should have started 8 weeks earlier to lower the clinical attack rate by 50%. In conclusion, vaccination timing was a critical factor in relation to the spread of the 2009 A(H1N1) influenza. Our results also corroborate the central role of children for the transmission of A(H1N1) pandemic influenza.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0030018PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3254636PMC
May 2012

Evaluation of the national surveillance system for point-prevalence of healthcare-associated infections in hospitals and in long-term care facilities for elderly in Norway, 2002-2008.

BMC Public Health 2011 Dec 13;11:923. Epub 2011 Dec 13.

Dept, of Hospital Epidemiology and Hygiene, National Center for Epidemiology, Budapest, Hungary.

Background: Since 2002, the Norwegian Institute of Public Health has invited all hospitals and long-term care facilities for elderly (LTCFs) to participate in two annual point-prevalence surveys covering the most frequent types of healthcare-associated infections (HAIs). In a comprehensive evaluation we assessed how well the system operates to meet its objectives.

Methods: Surveillance protocols and the national database were reviewed. Data managers at national level, infection control practitioners and ward personnel in hospitals as well as contact persons in LTCFs involved in prevalence data collection were surveyed.

Results: The evaluation showed that the system was structurally simple, flexible and accepted by the key partners. On average 87% of hospitals and 32% of LTCFs participated in 2004-2008; high level of data completeness was achieved. The data collected described trends in the prevalence of reportable HAIs in Norway and informed policy makers. Local results were used in hospitals to implement targeted infection control measures and to argue for more resources to a greater extent than in LTCFs. Both the use of simplified Centers for Disease Control and Prevention (CDC) definitions and validity of data seemed problematic as compliance with the standard methodology were reportedly low.

Conclusions: The surveillance system provides important information on selected HAIs in Norway. The system is overall functional and well-established in hospitals, however, requires active promotion in LTCFs. Validity of data needs to be controlled in the participating institutions before reporting to the national level.
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http://dx.doi.org/10.1186/1471-2458-11-923DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3265568PMC
December 2011

[The pandemic in Austevoll].

Tidsskr Nor Laegeforen 2011 Jun;131(12):1180

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http://dx.doi.org/10.4045/tidsskr.11.0524DOI Listing
June 2011

Contaminated mouth swabs caused a multi-hospital outbreak of Pseudomonas aeruginosa infection.

Authors:
Bjørn G Iversen

J Oral Microbiol 2010 Apr 20;2. Epub 2010 Apr 20.

Department of Infectious Disease Epidemiology, Norwegian Institute of Public Health, Oslo, Norway.

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http://dx.doi.org/10.3402/jom.v2i0.5123DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3084570PMC
April 2010

Questions on causality and responsibility arising from an outbreak of Pseudomonas aeruginosa infections in Norway.

Emerg Themes Epidemiol 2008 Oct 23;5:22. Epub 2008 Oct 23.

Norwegian Institute of Public Health, Oslo, Norway.

In 2002, Norway experienced a large outbreak of Pseudomonas aeruginosa infections in hospitals with 231 confirmed cases. This fuelled intense public and professional debates on what were the causes and who were responsible. In epidemiology, other sciences, in philosophy and in law there is a long tradition of discussing the concept of causality. We use this outbreak as a case; apply various theories of causality from different disciplines to discuss the roles and responsibilities of some of the parties involved. Mackie's concept of INUS conditions, Hill's nine viewpoints to study association for claiming causation, deterministic and probabilistic ways of reasoning, all shed light on the issues of causality in this outbreak. Moreover, applying legal theories of causation (counterfactual reasoning and the "but-for" test and the NESS test) proved especially useful, but the case also illustrated the weaknesses of the various theories of causation.We conclude that many factors contributed to causing the outbreak, but that contamination of a medical device in the production facility was the major necessary condition. The reuse of the medical device in hospitals contributed primarily to the size of the outbreak. The unintended error by its producer--and to a minor extent by the hospital practice--was mainly due to non-application of relevant knowledge and skills, and appears to constitute professional negligence. Due to criminal procedure laws and other factors outside the discourse of causality, no one was criminally charged for the outbreak which caused much suffering and shortening the life of at least 34 people.
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http://dx.doi.org/10.1186/1742-7622-5-22DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2585074PMC
October 2008

Nationwide study of invasive Pseudomonas aeruginosa infection in Norway: importance of underlying disease.

J Infect 2008 Aug 9;57(2):139-46. Epub 2008 Jul 9.

Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, NO-0403 Oslo, Norway.

Objective: Pseudomonas aeruginosa is an opportunistic pathogen that may cause invasive disease. We describe the epidemiology of invasive P. aeruginosa infection in Norway and identify associated clinical factors.

Methods: All patients with invasive P. aeruginosa and Pseudomonas not identified at the species level (Pseudomonas spp.) in Norway 1992-2002 were included. Detailed information was collected for all cases during 1999-2002. Population and health institution statistics were obtained from national databases.

Results: In 1999-2002 the incidence rate was 3.16 per 100 000 person-years at risk or 0.20 per 1000 hospital stays. For hospital-acquired infection the rate was 671 per 100 000 person-years as compared with 1.13 for community-acquired infection, and 37 in nursing homes. The highest risk for invasive Pseudomonas disease was found in patients with malignant neoplasms of lymphoid and haematopoietic tissue (risk per 1000 hospital stays 1.9; 95% CI 1.5-2.3) and other diseases of blood and blood-forming organs (2.2; 95% CI 1.2-3.7). The case fatality rate was 35%.

Conclusions: The incidence of invasive P. aeruginosa infection in this population-based study was much lower than in most single-hospital studies. The nationwide study design and prudent antibiotic use may explain some of the difference. Infection risk is strongly associated with certain underlying diseases.
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http://dx.doi.org/10.1016/j.jinf.2008.05.010DOI Listing
August 2008

Pseudomonas aeruginosa contamination of mouth swabs during production causing a major outbreak.

Ann Clin Microbiol Antimicrob 2007 Mar 13;6. Epub 2007 Mar 13.

Division of Infectious Disease Control, Norwegian Institute of Public Health, Oslo, Norway.

Background: In 2002 we investigated an outbreak comprising 231 patients in Norway, caused by Pseudomonas aeruginosa and linked to the use of contaminated mouth swabs called Dent-O-Sept. Here we describe the extent of contamination of the swabs, and identify critical points in the production process that made the contamination possible, in order to prevent future outbreaks.

Methods: Environmental investigation with microbiological examination of production, ingredients and product, molecular typing of bacteria and a system audit of production.

Results: Of the 1565 swabs examined from 149 different production batches the outbreak strain of P. aeruginosa was detected in 76 swabs from 12 batches produced in 2001 and 2002. In total more than 250 swabs were contaminated with one or more microbial species. P. aeruginosa was detected from different spots along the production line. The audit revealed serious breeches of production regulations. Health care institutions reported non-proper use of the swabs and weaknesses in their purchasing systems.

Conclusion: Biofilm formation in the wet part of the production is the most plausible explanation for the continuous contamination of the swabs with P. aeruginosa over a period of at least 30 weeks. When not abiding to production regulations fatal consequences for the users may ensue. For the most vulnerable patient groups only documented quality-controlled, high-level disinfected products and items should be used in the oropharynx.
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http://dx.doi.org/10.1186/1476-0711-6-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1831477PMC
March 2007

An outbreak of Pseudomonas aeruginosa infection caused by contaminated mouth swabs.

Clin Infect Dis 2007 Mar 1;44(6):794-801. Epub 2007 Feb 1.

Norwegian Institute of Public Health, Oslo, Norway.

Background: Pseudomonas aeruginosa is an opportunistic bacterium that can cause severe infection in susceptible patients. During the winter of 2001-2002, we investigated an outbreak of P. aeruginosa infection among patients in several hospitals across Norway.

Methods: A nationwide outbreak investigation was performed with case finding, questionnaires, and product sampling. All available clinical and environmental P. aeruginosa strains were genotyped. Detailed information was collected from patients with the outbreak strain or with any P. aeruginosa in blood or cerebrospinal fluid samples. To identify risk factors, we conducted a case-control study among patients with P. aeruginosa isolated from blood or cerebrospinal fluid samples during October 2001-December 2002. Case patients were patients infected with the outbreak genotype, and control subjects were patients infected with other genotypes.

Results: A total of 231 patients from 24 hospitals were identified as having the outbreak strain; 39 of these patients had positive blood culture results. Seventy-one patients (31%) died while hospitalized; all of the patients who died had severe underlying disease. Among 39 case patients and 159 control subjects, use of the moist mouth swab (adjusted odds ratio, 5.3; 95% confidence interval, 2.0-13.6) and receipt of mechanical ventilation (adjusted odds ratio, 6.4; 95% confidence interval, 2.3-17.2) were associated with infection due to the outbreak strain. Genotypically identical strains of P. aeruginosa were identified in 76 mouth swabs from 12 different batches and from the production line.

Conclusions: Contamination of mouth swabs during production caused the largest-ever outbreak of P. aeruginosa infection in Norway. Susceptible patient groups should use only documented quality-controlled, high-level-disinfected products and items in the oropharynx.
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http://dx.doi.org/10.1086/511644DOI Listing
March 2007

[Hospital infections in Norway 1999 and 2000].

Tidsskr Nor Laegeforen 2002 Oct;122(25):2440-3

Seksjon for forebyggende infeksjonsmedisin, Nasjonalt folkehelseinstitutt, Postboks 4404 Nydalen, 0403 Oslo.

Background: The objective of this investigation was to measure the prevalence of hospital acquired infections in Norway in 1999 and 2000.

Material And Methods: The results are based on prevalence reports sent to the Norwegian Institute of Public Health from 41 hospitals in 1999 and 45 in 2000, out of a total of 80 somatic hospitals. With the exception of two hospitals, all registered the four most common hospital infections: urinary tract infection, respiratory tract infection, surgical site infection, and septicaemia. In 1999, 35,612 patients were included; in 2000 35,712.

Results: The prevalence of the four most common hospital infections was 5.4% in 1999 and 5.1% in 2000. Urinary tract infections accounted for about 36.5% of all infections during both years.

Interpretation: About one in every 20 patients has at any given time a hospital infection. This report identifies the distribution of hospital infections and where to initiate further preventive measures.
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October 2002