I’m not claiming that the current H5N1 strain in the U.S. was genetically engineered to be easily transmissible between humans and so far it doesn’t appear to have been with only three cases in two years but it is entirely within the realm of possibility for it to occur. It was just a little over a decade ago now that a group of virologists at Erasmus Medical Centre in Rotterdam (Netherlands) introduced five mutations in two genes of the virus and made it aerosol transmissible in an experimental ferret colony. USG had parts of the published study redacted but similar research with similar results was carried out in other countries. It H5N1 ever becomes a pandemic it will probably not be natural.
UK Independent: Alarm as Dutch Lab creates highly contagious Killer Flu