# 4506
If you’ve followed the H1N1 story much over the past six months, you are no doubt aware of the concerns over the so called `Norwegian mutation’ – a single amino acid change in the HA1 gene at position 222 (225 in H3 numbering) from aspartic acid (D) to glycine (G).
While this mutation had been seen before and in other countries, it was in Norway last November that scientists announced a suspected link between this mutation and the virulence of the pandemic virus (see Norway Reports An H1N1 Mutation).
Since then we’ve seen conflicting evidence and a good deal of debate regarding the significance this mutation.
In a World Health Organization’s recent (No. 4, 2010, 85, 21–28) Weekly Epidemiological Record (WER), we get an update on this mutation.
While noting that it is worthy of further study (along with other mutations to the virus), for now the WHO’s position is that `Based on currently available virological, epidemiological and clinical information, the D222G substitution does not appear to pose a major public health issue.’
That is not to say that the book has been closed on this mutation. Certainly not. Only that – at this point in time – WHO scientists find insufficient evidence to link this mutation to greater virulence in the H1N1 virus.
Once again, scientists from Norway have announced new findings that they claim suggest a link between the severity of the virus and this mutation. Not all scientists share their in their conclusions, however.
Robert Roos from CIDRAP news sorts all of this out for us (as best as can be done at this stage, anyway), with a terrific piece on both sides of this growing debate.
H1N1 mutation's proposed link to severe illness debated
Robert Roos
News Editor
Mar 4, 2010 (CIDRAP News) – Norwegian scientists today reported a pandemic H1N1 virus mutation that appears to be associated with severe disease, but a leading US flu expert said global data on the mutation don't show a clear connection with severe illness.
A team from the Norwegian Institute of Public Health in Oslo reports that it found the mutation in 11 of 61 severe illness cases that were analyzed between July and December 2009. The mutation was not found in any of 205 mild cases that were analyzed between May 2009 and January 2010.
"This difference is statistically significant and our data are consistent with a possible relationship between this mutation and the clinical outcome," says the report by A. Kilander and colleagues, published today in Eurosurveillance. "To our knowledge, this is the first identification of a change in the pandemic virus that correlates with a severe clinical outcome."
However, Dr. Nancy Cox, director of the Influenza Division at the US Centers for Disease Control and Prevention (CDC), said global H1N1 data so far do not show a clear association between the mutation and severe illness.
"If you look globally you can see that this mutation is neither necessary nor sufficient for a severe or fatal outcome," Cox told CIDRAP News.
