VX-787 is not a vaccine. It is an orally available antiviral.
Tamiflu and Relenza are the only antivirals against influenza at this time. Relenza has an advantage over Tamiflu in viral resistance, but it has to be delivered by inhalation, and cannot be used for flu suffers with pulmonary symptoms. Tamiflu is an oral drug as VX-787 is, but it is useless because of global development of flu viral resistance (read my quotes from Science below).
Both flu drugs above are effective only if administered within two days of start of flu symptoms. VX-787 has been shown to be effective up to 4 days after infection in preclinical studies. If 787 is shown to be safe and effective in human, its market potential is enormous.
[[… The evolutionary ancestry of seasonal H1N1 influenza A virus lies with the devastating pandemic of 1918. Although the 1918 virus eventually died out in the 1950s, the H1N1 lineage reappeared in 1977 and has since circulated with H3N2 influenza A virus, and more recently with the newly emerged swine-origin pandemic H1N1/09 virus. Although seasonal H1N1 is associated with lower mortality than either the H3N2 or pandemic H1N1/09 viruses, in some years it is the dominant strain infecting humans and a considerable public health concern. [It was therefore worrying that in the winter of 2007–2008, the influenza season in the Northern Hemisphere, reports of oseltamivir resistance in seasonal H1N1 began to appear in northern Europe and in patients who had not received oseltamivir (2, 3).] By the following 2008–2009 influenza season, it was clear that seasonal H1N1 virus was resistant to oseltamivir on a global scale (4–6), effectively ruling out further use of this frontline antiviral drug. ]]