One H1N1 (2009) influenza virus isolated in Northern Ireland showed a reduced reactivity with the antibodies related to vaccine strain, ECDC said.

[Giuseppe]

Full ECDC report: http://www.ecdc.europa.eu/en/public...enza_virus_characterisation_2010_December.pdf
Full text at FluTrackers.com: http://www.flutrackers.com/forum/showthread.php?t=158753
Tables and phylogenetic trees: http://www.flutrackers.com/forum/showthread.php?t=158751

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The results show that the vast majority of viruses had similar levels and patterns of reactivity to the antisera and remained antigenically similar to the vaccine virus A/California/7/2009.

One virus?A/Northern Ireland/1/2010?showed a reduced level of reactivity with the majority of sera; sequencing of this virus is ongoing.

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Two viruses from England collected in November are shown in the phylogenetic tree; these viruses do not cluster together. The genetic characteristics of viruses isolated more recently in the UK have been described elsewhere (Ellis J, Galiano M, Pebody R, et al; Virological analysis of fatal influenza cases in the United Kingdom during the early wave of influenza in winter 2010/11. EuroSurveill. 2011;16(1): pii=19760.)

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[cartski]

Re: One H1N1 (2009) influenza virus isolated in Northern Ireland showed a reduced reactivity with the antibodies related to vaccine strain, ECDC said.

http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=19760

Conclusions:

Influenza virus circulation is underway in the UK and is contributing to seasonal winter pressures in the health system. The circulation of other winter viruses such as respiratory syncytial virus (RSV) and the particularly cold weather are also contributing. The virological picture is complex, with many strains of influenza virus circulating but no antigenic change in the influenza A(H1N1)2009 virus, and no immediately obvious genetic differences between viruses recovered from fatal cases and those causing mild illness.

The picture of the illness associated with influenza A(H1N1)2009 infection is consistent with what was seen in the 2009 pandemic, with a similar demographic impact, particularly affecting children and young adults. Whilst young age groups have the least experience of influenza and are recognised as important in the transmission of influenza, it is also possible that propensity to consult a doctor is greatest in younger age groups. Although the remaining susceptibles in the age group under 15 year account for high rates of positivity in peak weeks in community samples (as is often the case during seasonal influenza), it is notable that overall, sustained high rates of positivity are most marked in the age group between 15 and 44 years. This is in contrast to earlier pandemic waves in 2009 when highest rates of positivity in the community were observed in the 5-14 year-olds. The age group of 15-44 year-olds is also clearly the major group contributing to hospital admissions and deaths. The increase in requirement for critical care in the current season reflects the impact of influenza A(H1N1)2009 illness in the remaining susceptible young adults (15-44 years) and risk groups in the population.

Most of those with severe illness, and those dying, have not previously been vaccinated against influenza and have not had the benefit of the early use of antiviral drugs. Countries in Europe yet to experience substantial influenza activity this winter may wish to take all reasonable measures to increase the uptake of seasonal influenza vaccine in those at high risk of the complications of influenza and to ensure that antiviral drugs are readily available for those who are either severely ill or at increased risk of severe illness from influenza.

Further analysis of the antigenic and genetic properties of all influenza viruses from hospitalised patients, outbreaks and community cases is ongoing.

 

[Giuseppe]

Re: One H1N1 (2009) influenza virus isolated in Northern Ireland showed a reduced reactivity with the antibodies related to vaccine strain, ECDC said.

The ECDC reported that some of the most recent isolates from UK had a somewhat reduced reactivity with reference vaccine strain produced antibodies. This is a new development that must be taken into account, coupled with the increased genetic heterogeneity among H1N1 (2009) isolated in the European Region.