My Father Is 65 Years Old And Was Diagnosed With

my father is 65 years old and was diagnosed with right mid zone opacity in the lung x ray,my father had fever with shivers, cough etc two weeks prior to that. doc concluded it is pneumonia and took intravenous antibiotics injections and few tablets for 6 days. took a repeat x ray in three weeks time and concluded that the x ray looks clear now following the medication, is there anything to be worried about once the x ray is clear. my father is planning to travel to Australia during winter, would it affect his health further, he has taken flue vaccine now as advised .please advise