# 4196
The ECDC (European Centre For Disease Prevention & Control) like many agencies, took some time off last week and did not issue any daily reports on Thursday and Friday. So today’s update covers the events of the past 5 days.
Main developments in the past 5 days
Weekly Influenza Surveillance Overview published December 24th and covering Week 51 (Dec 14th to 20th) found that most reporting countries were observing declining trends with the most reported influenza activity being in South Eastern Europe
A total of 1 803 fatal cases in Europe and EFTA countries and 10 879 in the rest of the world have been reported up to date.
ECDC published a summary on the D222G/D222N mutations in the pandemic virus
Perhaps of most interest is the latest report on the D222G/D222N mutations in the pandemic virus.
While the ECDC believes that further study of these mutations and surveillance is warranted, they believe that as of right now, they should have a minimal impact on public health and pandemic response.
They find no direct evidence that these mutations are responsible for an increase in virulence (although they leave that door open a bit), or that they are being transmitted easily.
Here is the ECDC summary, and a more complete report is available here.
(slightly reformatted for readability).
ECDC Summary on Pandemic 2009 Virus Mutation D222G/D222N published in its Public Health Developments SeriesDecember 23rd
Recently, several countries have reported finding mutations of the 2009 pandemic virus. One particular mutation has come to attention, especially following a formal notification by Norway through the International Health Regulations and Early Warning and Response System reporting mechanisms.(1)
The particular change a substitutions in a specific codon of the Haemagglutinin (HA) gene and is called either D222G and D222N depending on the precise change. The variants have been especially found in a number of severe cases of pandemic influenza including deaths and it has been suggested that the variants could cause more efficient infection of deeper airways resulting in a more serious disease profile.
No direct evidence for this exists and cases have also been found in mild infections. The D222G and D222N variants, and sometimes mixtures thereof have been described in viruses and sequences derived directly from clinical specimens of 2009 pandemic influenza A(H1N1) cases in at least 20 countries, including Brazil, China, France, Italy, Japan, Mexico, Norway, Spain, the Ukraine and the USA.
These mutations are not new in this pandemic, they have been found in cased going back to April 2009.
To date no connection between cases, suggestive of transmission, has been found and it seems that the appearance in various countries is more the result of routine sequencing rather than spread of the mutation. It is also unclear if the association with severe cases is coincidental or not, perhaps resulting from preferred sequencing of specimens and viruses from severe cases/deaths.
After considering the current available virological, epidemiological and clinical findings and following discussions on an earlier draft with WHO and its European-based Collaborating Centre ECDC has come to a preliminary formulation namely that the G222D/N variants exist in a small proportion of sporadic severe, as well as mild cases of 2009 pandemic influenza A(H1N1) infection and that these represents natural variation of the virus with no special association with severity of the disease course.
As such and while they do not transmit they should have a minimal impact on public health and pandemic response. Current data suggests that the cases involving variant viruses in different parts of the world are unrelated and the underlying mutation events probably occurred independently from each other in the infected individuals as a consequence of the natural variability of influenza viruses and their inability to correct random coding errors.
However because of that inherent variability and ability to surprise the 2009 A(H1N1) will need on-going combined virological, epidemiological and clinical surveillance and study.(2)
1. WHO Pandemic (H1N1) 2009 briefing note 17.
http://www.who.int/csr/disease/swineflu/notes/briefing_20091120/en/index.html
2. ECDC 2009 pandemic influenza A(H1N1) virus mutations reported to be associated with severe disease ECDC Public Health development December 23rd 2009
