In clinical studies in which some of the vaccinees received Infanrix hexa concomitantly with Prevenar as a booster (4th) dose of both vaccines, fever ≥ 38.0°C was reported following 43.4% of doses in infants receiving Prevenar and Infanrix hexa at the same time as compared to 30.5% of doses in infants receiving the hexavalent vaccine alone.