Pandemic vaccination strategies and influenza severe outcomes during the influenza A(H1N1)pdm09 pandemic and the post-pandemic influenza season: the Nordic experience.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked DownloadDuring the 2009/10 influenza A(H1N1)pdm09 pandemic, the five Nordic countries adopted different approaches to pandemic vaccination. We compared pandemic vaccination strategies and severe influenza outcomes, in seasons 2009/10 and 2010/11 in these countries with similar influenza surveillance systems. We calculated the cumulative pandemic vaccination coverage in 2009/10 and cumulative incidence rates of laboratory confirmed A(H1N1)pdm09 infections, intensive care unit (ICU) admissions and deaths in 2009/10 and 2010/11. We estimated incidence risk ratios (IRR) in a Poisson regression model to compare those indicators between Denmark and the other countries. The vaccination coverage was lower in Denmark (6.1%) compared with Finland (48.2%), Iceland (44.1%), Norway (41.3%) and Sweden (60.0%). In 2009/10 Denmark had a similar cumulative incidence of A(H1N1)pdm09 ICU admissions and deaths compared with the other countries. In 2010/11 Denmark had a significantly higher cumulative incidence of A(H1N1)pdm09 ICU admissions (IRR: 2.4; 95% confidence interval (CI): 1.9-3.0) and deaths (IRR: 8.3; 95% CI: 5.1-13.5). Compared with Denmark, the other countries had higher pandemic vaccination coverage and experienced less A(H1N1)pdm09-related severe outcomes in 2010/11. Pandemic vaccination may have had an impact on severe influenza outcomes in the post-pandemic season. Surveillance of severe outcomes may be used to compare the impact of influenza between seasons and support different vaccination strategies

Burden of medically attended influenza in Norway 2008‐2017

Background The burden of influenza in Norway remains uncertain, and data on seasonal variations and differences by age groups are needed. Objective To describe number of patients diagnosed with influenza in Norway each season and the number treated in primary or specialist health care by age. Further, to compare the burden of seasonal influenza with the 2009‐2010 pandemic outbreak. Methods We used Norwegian national health registries and identified all patients diagnosed with influenza from 2008 to 2017. We calculated seasonal rates, compared hospitalized patients with patients in primary care and compared seasonal influenza with the 2009‐2010 pandemic outbreak. Results Each season, on average 1.7% of the population were diagnosed with influenza in primary care, the average rate of hospitalization was 48 per 100 000 population while the average number of hospitalized patients each season was nearly 2500. The number of hospitalized influenza patients ranged from 579 in 2008‐2009 to 4973 in 2016‐2017. Rates in primary care were highest among young adults while hospitalization rates were highest in patients 80 years and older and in children below 5 years. The majority of in‐hospital deaths were in patients 70 years and older. Fewer patients were hospitalized during the 2009‐2010 pandemic than in seasonal outbreaks, but during the pandemic, more people in the younger age groups were hospitalized and fatal cases were younger. Conclusion Influenza causes a substantial burden in primary care and hospitals. In non‐pandemic seasons, people above 80 years have the highest risk of influenza hospitalization and death

Human to animal transmission of influenza A(H1N1)pdm09 in a turkey breeder flock in Norway

Introduction: Routine surveillance samples disclosed seropositivity to influenza A virus (IAV) in a Norwegian turkey breeder flock. Simultaneous reports of influenza-like symptoms in farm workers and a laboratory confirmed influenza A(H1N1)pdm09 (H1N1pdm09) infection in one person led to the suspicion of a H1N1pdm09 infection in the turkeys. Animals and methods: H1N1pdm09 infection was confirmed by a positive haemaggutinin inhibition test using H1N1pdm09 antigens, and detection of H1N1pdm09 nucleic acid in reproductive organs of turkey hens. The flock showed no clinical signs except for a temporary drop in egg production. Previous reports of H1N1pdm09 infection in turkeys suggested human-to-turkey transmission (anthroponosis) during artificial insemination. Results and discussion: The flock remained seropositive to IAV and the homologous H1N1pdm09 antigen throughout the following 106 days, with decreasing seroprevalence over time. IAV was not detected in fertilised eggs or in turkey poults from the farm, however, maternally derived antibodies against H1N1pdm09 were found in egg yolks and in day-old poults. Genetic analyses of haemagglutinin gene sequences from one of the infected farm workers and turkeys revealed a close phylogenetic relationship, and confirmed human-to-turkey virus transmission

Influenza vaccination of elderly and people with chronic illness

1-PAGE KEY MESSAGES: This review presents the available documentation of the health effects of influenza vaccination to the elderly and people suffering from chronic illness. We searched for systematic reviews of the effects of influenza vaccine to the elderly and chronic ill. We updated the systematic reviews that we included, and we searched for randomized controlled trials (RCTs) of the effect of influenza vaccine to people with chronic illness. We included the following outcomes; all cause mortality, complications due to influenza (pneumonia), hospital admissions, influenza (laboratory confirmed), influenza like illness and adverse events. We included five systematic reviews that assessed the effect of influenza vaccination to the elderly, to people with chronic obstructive lung disease, asthma, bronchiectasis, and cystic fibrosis. We included one RCT and 12 observational studies for update of the effect of influenza vaccination on elderly. We additionally included four RCTs where the effect had been measured in people with cirrhosis of the liver, multiple sclerosis, HIV- infection, and cardio vascular disease. The evidence for influenza vaccine to elderly included more than 2,5 million people who had been included in six RCTs and 60 observational studies. Results indicate that influenza vaccine possibly reduce the risk of influenza and influenza like illness for community dwelling elderly. Influenza vaccine does possibly not influence the risk of all cause mortality or pneumonia for community dwelling elderly. Influenza vaccine possibly reduce the risk of influenza like illness for elderly living in institution, people with chronic hearth disease and people with HIV-infection. The quality of the evidence is low and very low, and results are uncertain. For the other outcomes and the other chronic diseases, evidence were either lacking or of very low quality. The evidence regarding effect of influenza vaccine to elderly and people with chronic illness is sparse