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Paradigm Shift Intervention Monitoring
The recent H1N1 outbreaks in Mexico
have raised concerns that a novel and virulent H1N1 is rapidly
spreading throughout the region. This concern has generated
serious vaccination campaigns in both countries. However,
recently released sequence by the US Air Force included five
isolates with the novel sub-clade. Included in the five were
two isolates from vaccinated patients (44M and 37M) in Arizona, A/Arizona/AF21768/2011, and New Jersey, A/New
The novel sub-clade contains four non-synonymous changes, N34D, S165N, A189T, and V275I, which are present in all of the recent isolates (mid 2010 through 2011). The New Jersey HA sequence has only the four changes noted above, indicating all novel sub-clade members have all changes required to generate a vaccine breakthrough (failure). This failure is likely linked to A189T, which is adjacent to receptor binding position 190, and S165N, which creates a new glycosylation site. Thus, it is ikely that the vaccination efforts in Chihuahua, Mexico and Venezuela will have limited success.
Moreover, anecdotal reports indicates that the novel sub-clade in Mexico is also causing outbreaks in Venezuela as well as multiple countries in Central and South America, signaling rapid spread of this H1N1 sub-clade in a pattern that mirrors the spread of H1N1 in 2009.
In addition, anecdotal reports indicate D225N is over-represented in these cases, raising concerns of an increased frequency of severe and fatal cases, as seen in Chihuahua, Mexico.
Release of 2011 sequences by the CDC, as well as other countries reporting an increase of H1N1 activity in the past several weeks is overdue.