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In an open access perspective article appearing in the journal mBio, well known NIH scientists and researchers David M. Morens, Jeffery K. Taubenberger, and Anthony S. Fauci give their take on the future of the novel 2009 H1N1 virus.
The 2009 H1N1 Pandemic Influenza Virus: What Next?
ABSTRACT
History suggests that the 2009 pandemic H1N1 influenza virus faces extinction unless it mutates to avoid already high global population immunity. The immune escape mechanisms potentially at its disposal include antigenic drift, antigenic shift via genetic reassortment, and intrasubtypic reassortment.
Going back to the late 19th century, the evolutionary histories of past pandemic viruses are examined in an effort to better understand the nature and extent of the immune pressures faced by the 2009 pandemic virus in the immediate future.
While human influenza viruses have often surprised us, available evidence leads to the hope that the current pandemic virus will continue to cause low or moderate mortality rates if it does not become extinct.
The FULL TEXT is available here.
For those who prefer the Press Release condensed version, we have that as well:
NIH scientists consider fate of pandemic H1N1 flu virus
Whither pandemic H1N1 virus? In a new commentary, scientists from the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, review the fates of previous pandemic influenza viruses in the years following a pandemic and speculate on possible future courses for the 2009 pandemic H1N1 (pH1N1) virus during the upcoming flu season and beyond.
The authors estimate that at least 183 million Americans (about 59 percent of the total U.S. population) have some immunity to pH1N1 because they were exposed to related viruses or vaccines prior to 2009, were immunized against pH1N1 or developed immunity following infection with the pandemic virus.
To stay in circulation in the face of such high levels of population immunity, the pH1N1 virus must adapt either through abrupt or gradual changes. The authors briefly examine a number of earlier pandemics and trace paths taken by the causative viruses. Some—for reasons not well understood—died out, while others, like those of 1889 and 1918, returned in an explosive fashion. Such an explosive return of pH1N1 virus is unlikely, note the authors, because global levels of immunity are already high and will increase further through immunization with 2010-2011 seasonal influenza vaccines, which contain the pH1N1 strain.
In light of what is known about pH1N1, the NIAID authors express a cautious optimism that unless it disappears entirely the virus will follow a route like that of 1968 pandemic virus, that is, it will persist in a form that causes relatively few deaths.
Nevertheless, the authors caution against complacency. As they acknowledge, many gaps remain in understanding how a given pandemic influenza virus adapts to increased immunity in humans. For that reason, influenza vaccination for everyone older than six months is a wise public health measure to maintain high levels of population-wide immunity. Immunization with 2010-2011 seasonal flu vaccine is particularly urged for babies older than six months, children, teens and young adults as the best way to protect individuals in those potentially more susceptible age groups from illness.
