Michael Callahan is a physician scientist boarded in medicine, ID, tropical medicine (DTM&H), Mass Casualty Care (DMC) and Rescue Medicine Command MD#17. Dr. Callahan's clinical appointments are at MGH/Harvard Medical School, and Visiting Professor at King Chulalongkorn Medical Center in Bangkok, Kaduna, Nigeria and Panama City, PN. His focus is emergency clinical trials for catastrophic infectious diseases such as Ebola, H5N1, MERS, Zika Virus, Chikungunya and complex dengue viral disease. He has developed drugs in market and expedited Phase 2 trials to support Animal Rule decisions.

In 2012 Dr. Callahan was recruited as President of Unither Virology a United Therapeutics company (UTHR), leading a R&D team executing a $45M NIH contract to accelerate a antiviral from lead to Phase 2 for dengue and flu, and to develop next-generation antivirals against RSV, Zika, Chikungunya and transplant-associated viral indications