scholarly journals Children under 10 years of age were more affected by the 2018/19 influenza A(H1N1)pdm09 epidemic in Canada: ‎possible cohort effect following the 2009 influenza pandemic

2019 ◽  
Vol 24 (15) ◽  
Author(s):  
Danuta M Skowronski ◽  
Siobhan Leir ◽  
Gaston De Serres ◽  
Michelle Murti ◽  
James A Dickinson ◽  
...  
Keyword(s):  
General Population ◽  
Influenza A ◽  
Influenza Pandemic ◽  
Age Distribution ◽  
Cohort Effect ◽  
Surveillance Network ◽  
Medical Visits ◽  
Influenza A H1n1 ◽  
2009 Influenza Pandemic ◽  
Negative Controls

Introduction Findings from the community-based Canadian Sentinel Practitioner Surveillance Network (SPSN) suggest children were more affected by the 2018/19 influenza A(H1N1)pdm09 epidemic. Aim To compare the age distribution of A(H1N1)pdm09 cases in 2018/19 to prior seasonal influenza epidemics in Canada. Methods The age distribution of unvaccinated influenza A(H1N1)pdm09 cases and test-negative controls were compared across A(H1N1)pdm09-dominant epidemics in 2018/19, 2015/16 and 2013/14 and with the general population of SPSN provinces. Similar comparisons were undertaken for influenza A(H3N2)-dominant epidemics. Results In 2018/19, more influenza A(H1N1)pdm09 cases were under 10 years old than controls (29% vs 16%; p < 0.001). In particular, children aged 5–9 years comprised 14% of cases, greater than their contribution to controls (4%) or the general population (5%) and at least twice their contribution in 2015/16 (7%; p < 0.001) or 2013/14 (5%; p < 0.001). Conversely, children aged 10–19 years (11% of the population) were under-represented among A(H1N1)pdm09 cases versus controls in 2018/19 (7% vs 12%; p < 0.001), 2015/16 (7% vs 13%; p < 0.001) and 2013/14 (9% vs 12%; p = 0.12). Conclusion Children under 10 years old contributed more to outpatient A(H1N1)pdm09 medical visits in 2018/19 than prior seasonal epidemics in Canada. In 2018/19, all children under 10 years old were born after the 2009 A(H1N1)pdm09 pandemic and therefore lacked pandemic-induced immunity. In addition, more than half those born after 2009 now attend school (i.e. 5–9-year-olds), a socio-behavioural context that may enhance transmission and did not apply during prior A(H1N1)pdm09 epidemics.

scholarly journals Pandemic influenza A(H1N1) 2009 breakthrough infections and estimates of vaccine effectiveness in Germany 2009-2010

2010 ◽  
Vol 15 (18) ◽  
Author(s):  
O Wichmann ◽  
P Stöcker ◽  
G Poggensee ◽  
D Altmann ◽  
D Walter ◽  
...  
Keyword(s):  
Pandemic Influenza ◽  
Influenza A ◽  
Influenza Pandemic ◽  
Rapid Assessment ◽  
Screening Method ◽  
Age Groups ◽  
Vaccine Effectiveness ◽  
Influenza A H1n1 ◽  
Reported Data ◽  
2009 Influenza Pandemic

During the 2009 influenza pandemic, a monovalent AS03-adjuvanted vaccine was almost exclusively used in Germany for immunisation against the 2009 pandemic influenza A(H1N1) virus. One-dose vaccination was recommended for all age groups. We applied the screening method for the rapid assessment of vaccine effectiveness (VE) based on reported data of vaccinated and unvaccinated pandemic influenza cases and vaccination coverage estimates. Preliminary results demonstrate excellent VE in persons aged 14-59 years (96.8%; 95% confidence interval (CI): 95.2-97.9) and moderately high VE in those 60 years or older (83.3%; 95% CI: 71.0-90.5).

scholarly journals Identification of Amino Acid Substitutions Supporting Antigenic Change of Influenza A(H1N1)pdm09 Viruses

2015 ◽  
Vol 89 (7) ◽  
pp. 3763-3775 ◽  
Author(s):  
Björn F. Koel ◽  
Ramona Mögling ◽  
Salin Chutinimitkul ◽  
Pieter L. Fraaij ◽  
David F. Burke ◽  
...  
Keyword(s):  
Amino Acid ◽  
Receptor Binding ◽  
Influenza A ◽  
Influenza Pandemic ◽  
Amino Acid Substitutions ◽  
Receptor Binding Site ◽  
Population Immunity ◽  
Influenza A H1n1 ◽  
Hemagglutinin Protein ◽  
2009 Influenza Pandemic

ABSTRACTThe majority of currently circulating influenza A(H1N1) viruses are antigenically similar to the virus that caused the 2009 influenza pandemic. However, antigenic variants are expected to emerge as population immunity increases. Amino acid substitutions in the hemagglutinin protein can result in escape from neutralizing antibodies, affect viral fitness, and change receptor preference. In this study, we constructed mutants with substitutions in the hemagglutinin of A/Netherlands/602/09 in an attenuated backbone to explore amino acid changes that may contribute to emergence of antigenic variants in the human population. Our analysis revealed that single substitutions affecting the loop that consists of amino acid positions 151 to 159 located adjacent to the receptor binding site caused escape from ferret and human antibodies elicited after primary A(H1N1)pdm09 virus infection. The majority of these substitutions resulted in similar or increased replication efficiencyin vitrocompared to that of the virus carrying the wild-type hemagglutinin and did not result in a change of receptor preference. However, none of the substitutions was sufficient for escape from the antibodies in sera from individuals that experienced both seasonal and pandemic A(H1N1) virus infections. These results suggest that antibodies directed against epitopes on seasonal A(H1N1) viruses contribute to neutralization of A(H1N1)pdm09 antigenic variants, thereby limiting the number of possible substitutions that could lead to escape from population immunity.IMPORTANCEInfluenza A viruses can cause significant morbidity and mortality in humans. Amino acid substitutions in the hemagglutinin protein can result in escape from antibody-mediated neutralization. This allows the virus to reinfect individuals that have acquired immunity to previously circulating strains through infection or vaccination. To date, the vast majority of A(H1N1)pdm09 strains remain antigenically similar to the virus that caused the 2009 influenza pandemic. However, antigenic variants are expected to emerge as a result of increasing population immunity. We show that single amino acid substitutions near the receptor binding site were sufficient to escape from antibodies specific for A(H1N1)pdm09 viruses but not from antibodies elicited in response to infections with seasonal A(H1N1) and A(H1N1)pdm09 viruses. This study identified substitutions in A(H1N1)pdm09 viruses that support escape from population immunity but also suggested that the number of potential escape variants is limited by previous exposure to seasonal A(H1N1) viruses.

scholarly journals Ratio of Excess ED ILI Visits to Seroprevalence, Influenza A/H1N1 Infection, FL, 2009

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Richard Hopkins ◽  
Aaron Kite-Powell ◽  
Kate Goodin ◽  
Janet J. Hamilton
Keyword(s):  
Emergency Department ◽  
Emergency Department Visit ◽  
Pandemic Influenza ◽  
Influenza A ◽  
Influenza Pandemic ◽  
H1n1 Infection ◽  
Influenza Like Illness ◽  
Influenza A H1n1 ◽  
2009 Influenza Pandemic

During the 2009 influenza pandemic, due to the 2009 pandemic influenza A (pH1N1) virus, there were an estimated 44 infections for every excess emergency department visit for influenza-like illness in Florida.

scholarly journals European Pandemic Influenza Preparedness Planning: A Review of National Plans, July 2016

2018 ◽  
Vol 13 (03) ◽  
pp. 582-592 ◽  
Author(s):  
Maaike Droogers ◽  
Massimo Ciotti ◽  
Peter Kreidl ◽  
Angeliki Melidou ◽  
Pasi Penttinen ◽  
...  
Keyword(s):  
Pandemic Influenza ◽  
Influenza A ◽  
Influenza Pandemic ◽  
Small Population ◽  
Pandemic Preparedness ◽  
Preparedness Planning ◽  
Influenza A H1n1 ◽  
Robust Planning ◽  
2009 Influenza Pandemic ◽  
The Impact

AbstractPandemic influenza A (H1N1) commenced in April 2009. Robust planning and preparedness are needed to minimize the impact of a pandemic. This study aims to review if key elements of pandemic preparedness are included in national plans of European countries. Key elements were identified before and during the evaluations of the 2009 pandemic and are defined in this study by 42 items. These items are used to score a total of 28 publicly available national pandemic influenza plans. We found that plans published before the 2009 influenza pandemic score lower than plans published after the pandemic. Plans from countries with a small population size score significantly lower compared to national plans from countries with a big population (P &lt;.05). We stress that the review of written plans does not reflect the actual preparedness level, as the level of preparedness entails much more than the existence of a plan. However, we do identify areas of improvement for the written plans, such as including aspects on the recovery and transition phase and several opportunities to improve coordination and communication, including a description of the handover of leadership from health to wider sector management and communication activities during the pre-pandemic phase. (Disaster Med Public Health Preparedness. 2019;13:582-592)

scholarly journals Influenza Vaccine Effectiveness and Waning Effect in Hospitalized Older Adults. Valencia Region, Spain, 2018/2019 Season

2021 ◽  
Vol 18 (3) ◽  
pp. 1129
Author(s):  
Ainara Mira-Iglesias ◽  
F. Xavier López-Labrador ◽  
Javier García-Rubio ◽  
Beatriz Mengual-Chuliá ◽  
Miguel Tortajada-Girbés ◽  
...  
Keyword(s):  
Older Adults ◽  
Influenza Vaccine ◽  
Influenza A ◽  
Vaccine Effectiveness ◽  
Surveillance Network ◽  
Adjuvanted Vaccine ◽  
Clinical Registries ◽  
Populations At Risk ◽  
Influenza A H1n1 ◽  
Hospitalized Older Adults

Influenza vaccination is annually recommended for specific populations at risk, such as older adults. We estimated the 2018/2019 influenza vaccine effectiveness (IVE) overall, by influenza subtype, type of vaccine, and by time elapsed since vaccination among subjects 65 years old or over in a multicenter prospective study in the Valencia Hospital Surveillance Network for the Study of Influenza and other Respiratory Viruses (VAHNSI, Spain). Information about potential confounders was obtained from clinical registries and/or by interviewing patients and vaccination details were only ascertained by registries. A test-negative design was performed in order to estimate IVE. As a result, IVE was estimated at 46% (95% confidence interval (CI): (16%, 66%)), 41% (95% CI: (−34%, 74%)), and 45% (95% CI: (7%, 67%)) against overall influenza, A(H1N1)pdm09 and A(H3N2), respectively. An intra-seasonal not relevant waning effect was detected. The IVE for the adjuvanted vaccine in ≥75 years old was 45% (2%, 69%) and for the non-adjuvanted vaccine in 65–74 years old was 59% (−16%, 86%). Thus, our data revealed moderate vaccine effectiveness against influenza A(H3N2) and not significant against A(H1N1)pdm09. Significant protection was conferred by the adjuvanted vaccine to patients ≥75 years old. Moreover, an intra-seasonal not relevant waning effect was detected, and a not significant IVE decreasing trend was observed over time.

scholarly journals Interim estimates of 2015/16 vaccine effectiveness against influenza A(H1N1)pdm09, Canada, February 2016

2016 ◽  
Vol 21 (11) ◽  
Author(s):  
Catharine Chambers ◽  
Danuta M Skowronski ◽  
Suzana Sabaiduc ◽  
Anne Luise Winter ◽  
James A Dickinson ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Northern Hemisphere ◽  
Influenza A ◽  
Vaccine Effectiveness ◽  
Genetic Evolution ◽  
Significant Protection ◽  
Surveillance Network ◽  
Potential Gain ◽  
Influenza A H1n1

Using a test-negative design, the Canadian Sentinel Practitioner Surveillance Network (SPSN) assessed interim 2015/16 vaccine effectiveness (VE) against influenza A(H1N1)pdm09 viruses. Adjusted VE showed significant protection of 64% (95% confidence interval (CI): 44–77%) overall and 56% (95%CI: 26–73%) for adults between 20 and 64 years-old against medically attended, laboratory-confirmed A(H1N1)pdm09 illness. Among the 67 A(H1N1)pdm09-positive specimens that were successfully sequenced, 62 (> 90%) belonged to the emerging genetic 6B.1 subclade, defined by S162N (potential gain of glycosylation) and I216T mutations in the haemagglutinin protein. Findings from the Canadian SPSN indicate that the 2015/16 northern hemisphere vaccine provided significant protection against A(H1N1)pdm09 illness despite genetic evolution in circulating viruses.

scholarly journals Roles of Different Transport Modes in the Spatial Spread of the 2009 Influenza A(H1N1) Pandemic in Mainland China

2019 ◽  
Vol 16 (2) ◽  
pp. 222 ◽  
Author(s):  
Jun Cai ◽  
Bo Xu ◽  
Karen Kie Yan Chan ◽  
Xueying Zhang ◽  
Bing Zhang ◽  
...  
Keyword(s):  
Significant Role ◽  
Influenza A ◽  
Influenza Pandemic ◽  
Mainland China ◽  
H1n1 Pandemic ◽  
Railway Stations ◽  
Early Arrival ◽  
Influenza A H1n1 ◽  
Transport Modes ◽  
Rail Travel

There is increasing concern about another influenza pandemic in China. However, the understanding of the roles of transport modes in the 2009 influenza A(H1N1) pandemic spread across mainland China is limited. Herein, we collected 127,797 laboratory-confirmed cases of influenza A(H1N1)pdm09 in mainland China from May 2009 to April 2010. Arrival days and peak days were calculated for all 340 prefectures to characterize the dissemination patterns of the pandemic. We first evaluated the effects of airports and railway stations on arrival days and peak days, and then we applied quantile regressions to quantify the relationships between arrival days and air, rail, and road travel. Our results showed that early arrival of the virus was not associated with an early incidence peak. Airports and railway stations in prefectures significantly advanced arrival days but had no significant impact on peak days. The pandemic spread across mainland China from the southeast to the northwest in two phases that were split at approximately 1 August 2009. Both air and road travel played a significant role in accelerating the spread during phases I and II, but rail travel was only significant during phase II. In conclusion, in addition to air and road travel, rail travel also played a significant role in accelerating influenza A(H1N1)pdm09 spread between prefectures. Establishing a multiscale mobility network that considers the competitive advantage of rail travel for mid to long distances is essential for understanding the influenza pandemic transmission in China.

Antigenic and genomic characterization of human influenza A and B viruses circulating in Argentina after the introduction of influenza A(H1N1)pdm09

2014 ◽  
Vol 63 (12) ◽  
pp. 1626-1637 ◽  
Author(s):  
Mara L. Russo ◽  
Andrea V. Pontoriero ◽  
Estefania Benedetti ◽  
Andrea Czech ◽  
Martin Avaro ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Influenza A ◽  
Vaccine Virus ◽  
Influenza Viruses ◽  
World Health ◽  
Influenza Surveillance ◽  
Human Influenza ◽  
Surveillance Network ◽  
Influenza A H1n1 ◽  
Health Organization

This study was conducted as part of the Argentinean Influenza and other Respiratory Viruses Surveillance Network, in the context of the Global Influenza Surveillance carried out by the World Health Organization (WHO). The objective was to study the activity and the antigenic and genomic characteristics of circulating viruses for three consecutive seasons (2010, 2011 and 2012) in order to investigate the emergence of influenza viral variants. During the study period, influenza virus circulation was detected from January to December. Influenza A and B, and all current subtypes of human influenza viruses, were present each year. Throughout the 2010 post-pandemic season, influenza A(H1N1)pdm09, unexpectedly, almost disappeared. The haemagglutinin (HA) of the A(H1N1)pdm09 viruses studied were segregated in a different genetic group to those identified during the 2009 pandemic, although they were still antigenically closely related to the vaccine strain A/California/07/2009. Influenza A(H3N2) viruses were the predominant strains circulating during the 2011 season, accounting for nearly 76 % of influenza viruses identified. That year, all HA sequences of the A(H3N2) viruses tested fell into the A/Victoria/208/2009 genetic clade, but remained antigenically related to A/Perth/16/2009 (reference vaccine recommended for this three-year period). A(H3N2) viruses isolated in 2012 were antigenically closely related to A/Victoria/361/2011, recommended by the WHO as the H3 component for the 2013 Southern Hemisphere formulation. B viruses belonging to the B/Victoria lineage circulated in 2010. A mixed circulation of viral variants of both B/Victoria and B/Yamagata lineages was detected in 2012, with the former being predominant. A(H1N1)pdm09 viruses remained antigenically closely related to the vaccine virus A/California/7/2009; A(H3N2) viruses continually evolved into new antigenic clusters and both B lineages, B/Victoria/2/87-like and B/Yamagata/16/88-like viruses, were observed during the study period. The virological surveillance showed that the majority of the circulating strains during the study period were antigenically related to the corresponding Southern Hemisphere vaccine strains except for the 2012 A(H3N2) viruses.

scholarly journals The return of the historic influenza A H1N1 virus and its impact on the population of the United Kingdom

1982 ◽  
Vol 89 (1) ◽  
pp. 89-100 ◽  
Author(s):  
P. Chakraverty ◽  
P. Cunningham ◽  
M. S. Pereira
Keyword(s):  
United Kingdom ◽  
Influenza A ◽  
Antigenic Variation ◽  
Adult Population ◽  
Age Distribution ◽  
Age Groups ◽  
The United Kingdom ◽  
Influenza A H1n1 ◽  
Older Adult Population ◽  
The Impact

SUMMARYThe epidemiology in the United Kingdom of the influenza A H1N1 subtype which returned in 1977 after an absence of 20 years is described for the four winter seasons from 1977/8 to 1980/1. The age distribution of virus isolates and the evidence for antigenic variation is presented. The impact in the susceptible age groups year by year is shown by the change in the population with specific antibody. There was the expected increase of antibody in those under the age of 21 but also evidence for a significant amount of infection or re-infection in the older adult population.

Hospital Capacity during an Influenza Pandemic—Buenos Aires, Argentina, 2009

2011 ◽  
Vol 32 (1) ◽  
pp. 87-90 ◽  
Author(s):  
Elissa Meites ◽  
Daniel Farias ◽  
Lucrecia Raffo ◽  
Rachel Albalak ◽  
Oreste Luis Carlino ◽  
...  
Keyword(s):  
Critical Care ◽  
Influenza A ◽  
Buenos Aires ◽  
Influenza Pandemic ◽  
Rapid Expansion ◽  
H1n1 Pandemic ◽  
Surge Capacity ◽  
Hospital Capacity ◽  
Preparedness Planning ◽  
Influenza A H1n1

At a major referral hospital in the Southern Hemisphere, the 2009 influenza A (H1N1) pandemic brought increased critical care demand and more unscheduled nursing absences. Because of careful preparedness planning, including rapid expansion and redistribution of the numbers of available beds and staff, hospital surge capacity was not exceeded.

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