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ECDC Risk Assessment On trH3N2 Cases In North America

 

 

# 5983

 


My thanks to Helen Branswell for tweeting the link to this new risk assessment from the ECDC on the recent trH3N2 cases detected in a handful of people (mostly children) across four states here in the US (see MMWR Dispatch: Limited H-2-H Transmission Of Novel A(H3N2) Virus.)

 

The 7-page PDF document considers the current threat these reassorted swine viruses pose to public health in Europe to be low.

 

They concede, however, that `It is possible that these triple reassortant infections will appear in Europe, particularly if there is more human-to- human  transmission, which could lead to imported cases.’

 

 

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ECDC rapid risk assessment: Swine-origin triple Reassortant influenza A(H3N2) viruses in North America

29 Nov 2011

Centers for Disease Control and Prevention (CDC) has reported recent infections in children in North America with a swine-origin triple reassortant influenza A(H3N2) virus that includes a genetic component from the pandemic 2009 virus, and with probable human-to-human transmission with these viruses.

 

ECDC has conducted a rapid risk assessment to evaluate the implications for public health in Europe.

ECDC rapid risk assessment: Swine-origin triple reassortant influenza A(H3N2) viruses in North America (29 November 2011)

A few excerpts from the summary follow, but the entire document is worth reading:

 

Conclusions and recommendations


Following recent infections in children in North America with a swine-origin triple reassortant influenza A(H3N2) virus that includes a genetic component from the pandemic 2009 virus, and with probable human-to-human transmission of these viruses, ECDC has come to the following preliminary opinion:


•  These viruses are known to be found in pigs in North America but they have not been found in pigs in Europe (EU/EEA countries). However, surveillance for influenza in pigs is weak in both North America and Europe, and surveillance for infections in humans in close contact with pigs is notably weak in Europe. Hence all such statements on the epidemiology of swine influenzas must be treated with caution.   

 

•  Most of the US cases experienced only mild disease. Those hospitalised had underlying conditions and all patients recovered completely.


•  These viruses are susceptible to the neuraminidase inhibitors (oseltamivir and zanamivir) though the current A(H3N2) component of seasonal influenza vaccines is unlikely to provide protection. Older people are likely to have some protection from exposure to earlier vaccines.


•  It is considered by the United States Centers for Disease Control (CDC) that there had already been some very limited human-to-human transmission of these and similar viruses in the US. 


•  Unlike in March 2009 (the start of the pandemic) there are no reports of numbers of unexplained influenza infections elsewhere in the Americas. Hence it is unlikely that these US cases represent outliers for a larger phenomenon. 


•  Overall, therefore, the immediate direct threat to human health in Europe is low.


•  ECDC staff are following the situation closely and are in direct contact with the WHO, the US CDC and relevant experts in EU Member States.


•  There is a need to ensure that these infections could be detected through  diagnostic testing in European national influenza laboratories. 


•  There are strong public health arguments for more active virological surveillance of pig herds in Europe (and North America) including active surveillance of infections in humans that are in direct or indirect contact with pigs.  

 
•  Equally justified are more formal approaches to assessing emerging influenza viruses for their pandemic potential and such virological risk assessments should continue to be developed. 

 

•  Unusual influenza viruses should continue to be referred to National Influenza Centres and on to the WHO Collaborating Centre in Europe, along with relevant clinical and epidemiological data.   

 

 

For more on this emerging  story, you wish to revisit some of these earlier blogs:

 

Pseudo Pandemics And Viral Interlopers
CDC Update On trH3N2 Swine Infections
CDC Update On trH3N2 Cases
CDC Update On Recent Novel Swine Flu Cases
MMWR: Swine-Origin Influenza A (H3N2) Virus Infection in Two Children

Related Post:

TRH3N2
ECDC
risk assessment

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