H7N9 comments from ASM 2013.

Prof Albert (Ab) Osterhaus noted during a panel at the American Society of Microbiology 2013 meeting in Denver, that an H7N9 virus capable of spreading efficiently from human-to-human might result in an enormous outbreak.
Prof Osterhaus pointed out that although H5N1 has been around for over a decade (and our research still has not answered all the questions we've raised) it still has not developed the ability to spread efficiently from human to human. He also feels that the "spillover" from birds (likely to be poultry) to humans is via the live bird markets (LBMs) in China-in some way. We must also be mindful of influenza being a seasonal infection so we may see a lull as we enter the warmer months but that it may return as the weather changes.
Prof Osterhaus also reminds us that "low-path" (low pathogenic avian influenza) virus are not necessarily "no-path" and that we shouldn't get too hung up on what may varies among, perhaps within, bird species as noted during lab studies. He also notes that the EMC team has developed a ferret model that provides human-relevant data on influenza infection and he stresses, continually, the importance of good epidemiology underpinned by ongoing surveillance systems.

Prof Robert Webster notes that LBMs may start to be reopened soon. He expressed his concern that H7N9 might re-emerge because of market reactivation. He also notes that poultry vaccines are "second-class" (Prof Osterhaus disagrees, says there arequality animal vaccines; H5N1 vaccines do not provide sterilising immunity - the chickens look good, but they keep shedding viruses - which is a hindrance to further vaccination of apparently healthy animals.

Dr Carole Heilman addresses the possibility of a universal vaccine noting that vaccines very conserved regions show promise in animals models. Current vaccine target the response to hemagglutinin - but what markers will be needed for vaccines focussing on eliciting other responses.

Prof Webster raises the issues of possibly "the most important avian influenza virus" H9N2, a virus spread ubiquitously across Eurasia, evolving in Bangladesh. H9N2 is stealthy in causing no apparent disease but is the backbone of H7N9. It may be the donor virus for many future reassortants.
Prof Osterhaus noted that much of what we have predicted about influenza virus over the years, hasn't happened-so lets keep predicting! However, H5N1 mutations, which are easy for the virus to accumulate, that could create an easily transmissible pandemic virus already exist in nature, some found in H7 and H9 viruses. Inexplicably, these mutations have not come together in humans yet. The potential exists however and complacency must be avoided.

In answer to a question expressing the public's concerns over escape or weaponization of lab-created "frankenflu" (my addition) viruses, Prof Osterhaus notes the high level of scrutiny and containment that these sorts of experiments are conducted under. He also notes that the biggest bioterrorist is nature.
In my opinion, the mutant flu virus research allows us to understand whether these mutations are possible and viable. The new viruses harbouring mutations of interest are "fit", they are able to replicate and transmit efficiently - some mutations make the virus less fit and so are unlikely to survive in nature. Understanding what is likely and what is not, helps researchers and public health officials develop policy, procedures and materials to be on guard for the greatest risks. Knowledge also helps us focus our research towards countering what could happen rather than stumbling around wasting time, effort and money on avenues that will not bear fruit in terms of increased public health and safety in an area that has a ticking clock a