travis bias london school of hygiene and tropical medicine, london, uk carl allen miranda medical centre, sydney, australia anna buckley consultant in emergency medicine, university college london hospital, london, uk alex hillman york hospital, york teaching hospital nhs foundation trust, york, uk tamsin lillie paediatric department, rotorua hospital, rotorua, new zealand immaculate goima muhimbili national hospital, dar es salaam, tanzania gissela nyakunga