The impact of the pandemic influenza A(H1N1) 2009 virus on seasonal influenza A viruses in the southern hemisphere, 2009

Data collected over winter 2009 by five World Health Organisation National Influenza Centres in the southern hemisphere were used to examine the circulation of pandemic and seasonal influenza A strains during the first pandemic wave in the southern hemisphere. There is compelling evidence that the pandemic influenza A(H1N1) 2009 virus significantly displaced seasonal influenza A(H1N1) and, to a lesser extent, A(H3N2) viruses circulating in the southern hemisphere. Complete replacement of seasonal influenza A strains, however, was not observed during the first pandemic wave.

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Pandemic influenza A(H1N1)v viruses currently circulating in New Zealand are sensitive to oseltamivir

Eurosurveillance ◽

10.2807/ese.14.30.19282-en ◽

2009 ◽

Vol 14 (30) ◽

Cited By ~ 9

Author(s):

R J Hall ◽

M P Peacey ◽

J C Ralston ◽

J Bocacao ◽

M Ziki ◽

...

Keyword(s):

New Zealand ◽

Southern Hemisphere ◽

Pandemic Influenza ◽

Influenza A ◽

Seasonal Influenza ◽

Antiviral Drug ◽

Temperate Climate ◽

Winter Period ◽

Influenza A H1n1 ◽

Influenza Activity

New Zealand, like other southern hemisphere countries with a temperate climate, has been in the winter period with seasonal influenza activity. New Zealand has also experienced a dramatic increase in the number of cases of pandemic influenza A(H1N1)v virus. Early reports from the northern hemisphere at the beginning of the pandemic showed that the virus was sensitive to the antiviral drug oseltamivir. In this study we report that pandemic influenza A(H1N1)v viruses currently circulating in New Zealand are sensitive to oseltamivir, but seasonal influenza A(H1N1) viruses – the co-circulating predominant seasonal strain, is resistant to oseltamivir.

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Estimating the impact of the 2009 influenza A(H1N1) pandemic on mortality in the elderly in Navarre, Spain

Eurosurveillance ◽

10.2807/ese.15.05.19481-en ◽

2010 ◽

Vol 15 (5) ◽

Author(s):

J Castilla ◽

J Etxeberria ◽

E Ardanaz ◽

Y Floristán ◽

R López Escudero ◽

...

Keyword(s):

Pandemic Influenza ◽

Influenza A ◽

Excess Mortality ◽

Seasonal Influenza ◽

The Elderly ◽

Significant Excess ◽

Influenza A H1n1 ◽

The Mean ◽

The Impact ◽

Second Wave

We analysed mortality among people aged 65 years or older in Navarre, Spain in 2009 and compared it with the mean for the same period of time in the previous three years. In the pandemic weeks 24 to 52 2009 we observed 4.9% more deaths than expected (p=0.0268). Excess mortality occurred during the circulation of seasonal influenza (8.0%, p=0.0367) and the first wave of pandemic influenza (9.9%, p=0.0079). In the second wave of pandemic influenza there was a non-significant excess of deaths (5.2%, p=0.1166). Surveillance of laboratory-confirmed severe influenza cases detected only one death in this age group.

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Use of an inactivated vaccine in mitigating pandemic influenza A(H1N1) spread: a modelling study to assess the impact of vaccination timing and prioritisation strategies

Eurosurveillance ◽

10.2807/ese.14.41.19356-en ◽

2009 ◽

Vol 14 (41) ◽

Author(s):

V Sypsa ◽

I Pavlopoulou ◽

A Hatzakis

Keyword(s):

Pandemic Influenza ◽

Influenza A ◽

Inactivated Vaccine ◽

Binary File ◽

Influenza A H1n1 ◽

The Impact ◽

Modelling Study

Binary file ES_Abstracts_Final_ECDC.txt matches

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Hospitalized Children with 2009 Pandemic Influenza A (H1N1): Comparison to Seasonal Influenza and Risk Factors for Admission to the ICU

PLoS ONE ◽

10.1371/journal.pone.0015173 ◽

2010 ◽

Vol 5 (12) ◽

pp. e15173 ◽

Cited By ~ 50

Author(s):

Dayanand Bagdure ◽

Donna J. Curtis ◽

Emily Dobyns ◽

Mary P. Glodé ◽

Samuel R. Dominguez

Keyword(s):

Risk Factors ◽

Pandemic Influenza ◽

Influenza A ◽

Seasonal Influenza ◽

Hospitalized Children ◽

Influenza A H1n1

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

Journal of Medical Microbiology ◽

10.1099/jmm.0.076208-0 ◽

2014 ◽

Vol 63 (12) ◽

pp. 1626-1637 ◽

Cited By ~ 3

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.

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Contemporary Seasonal Influenza A (H1N1) Virus Infection Primes for a More Robust Response To Split Inactivated Pandemic Influenza A (H1N1) Virus Vaccination in Ferrets

Clinical and Vaccine Immunology ◽

10.1128/cvi.00247-10 ◽

2010 ◽

Vol 17 (12) ◽

pp. 1998-2006 ◽

Cited By ~ 11

Author(s):

Ali H. Ellebedy ◽

Thomas P. Fabrizio ◽

Ghazi Kayali ◽

Thomas H. Oguin ◽

Scott A. Brown ◽

...

Keyword(s):

Influenza Virus ◽

Pandemic Influenza ◽

Influenza A ◽

Seasonal Influenza ◽

H1n1 Virus ◽

H1n1 Influenza ◽

Influenza Viruses ◽

Inactivated Vaccine ◽

H1n1 Influenza Virus ◽

Influenza A H1n1

ABSTRACT Human influenza pandemics occur when influenza viruses to which the population has little or no immunity emerge and acquire the ability to achieve human-to-human transmission. In April 2009, cases of a novel H1N1 influenza virus in children in the southwestern United States were reported. It was retrospectively shown that these cases represented the spread of this virus from an ongoing outbreak in Mexico. The emergence of the pandemic led to a number of national vaccination programs. Surprisingly, early human clinical trial data have shown that a single dose of nonadjuvanted pandemic influenza A (H1N1) 2009 monovalent inactivated vaccine (pMIV) has led to a seroprotective response in a majority of individuals, despite earlier studies showing a lack of cross-reactivity between seasonal and pandemic H1N1 viruses. Here we show that previous exposure to a contemporary seasonal H1N1 influenza virus and to a lesser degree a seasonal influenza virus trivalent inactivated vaccine is able to prime for a higher antibody response after a subsequent dose of pMIV in ferrets. The more protective response was partially dependent on the presence of CD8+ cells. Two doses of pMIV were also able to induce a detectable antibody response that provided protection from subsequent challenge. These data show that previous infection with seasonal H1N1 influenza viruses likely explains the requirement for only a single dose of pMIV in adults and that vaccination campaigns with the current pandemic influenza vaccines should reduce viral burden and disease severity in humans.

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