This retrospective pregnancy case described the occurrence of slow response to stimuli in a 8-week-old male infant. The mother was a subject enrolled in an open label study. The subject received maraviroc 25 mg from 15th August 2017 to 21st August 2017, for HIV infection. Co-suspect products included DTaP vaccine, Hepatitis B vaccine, Polio vaccine (oral or inactivated unknown), PCV-13 vaccine, Rotavirus vaccine and Hib vaccine. The pregnancy resulted in a  live neonate with no apparent congenital anomaly. At [weeks gestation], the infant was born via unknown delivery and weighed 2480 grams (5 lbs 7 oz) at birth. APGAR scores were 9 and 9. The infant was diagnosed with slow response to stimuli. Serious criteria included clinically significant/intervention required. Additional event(s) included tremor (on 12th October 2017, serious criteria clinically significant/intervention required) and cyanosis (on 12th October 2017, serious criteria clinically significant/intervention required). The outcome of slow response to stimuli was recovered/resolved on 16th October 2017. The outcome(s) of the additional event(s) included tremor (recovered/resolved on 16th October 2017) and cyanosis (recovered/resolved on 16th October 2017). The investigator considered the slow response to stimuli, tremor and cyanosis to be unrelated to maraviroc. Other possible cause(s) of the slow response to stimuli included Diphtheria toxoid 30 IU, Tetanus toxoid 40 IU, Pertussis toxoid 25 ug, Filamentous Haemagglutinin 25 ug, Pertactin 8 ug, Haemophilus influenzae type B vaccine, Hepatitis B vaccine, Poliomyelitis vaccine (oral or inactivated unknown) and Rotavirus vaccine. Other possible cause(s) of the tremor included Diphtheria toxoid 30 IU, Tetanus toxoid 40 IU, Pertussis toxoid 25 ug, Filamentous Haemagglutinin 25 ug, Pertactin 8 ug, Haemophilus influenzae type B vaccine, Hepatitis B vaccine, Poliomyelitis vaccine (oral or inactivated unknown) and Rotavirus vaccine. Other possible cause(s) of  the  cyanosis  included  Diphtheria toxoid 30  IU, Tetanus toxoid 40 IU, Pertussis toxoid 25 ug, Filamentous Haemagglutinin 25 ug, Pertactin 8 ug, Haemophilus influenzae type B vaccine, Hepatitis B  vaccine, Poliomyelitis vaccine (oral or inactivated  unknown) and Rotavirus vaccine. Additional information: Subject was brought to ER by ambulance after 911 call. Mother states after routine immunizations earlier that day and the infant slept most of the day. At approximately 2120 mom attempted to take axillary temperature and the infant woke up all of a sudden and let out a cry that was different than normal. The baby's arms and legs were flexed for what mother believes was 3 minutes. He turned purple including body, lips and extremities but was crying the entire time. A neighbour came to help and the infant was flipped onto stomach and his back was stroked. He then had copious salivation and purple skin colour resolved Mother states he looked pale and dazed for 5-10 minutes before returning to baseline. Mother thought it may have been a seizure and infant's maternal aunt has seizure disorder. Once in the physical examination and vital signs were normal and the infant was quiet and comfortable. The infant was sent to the observation area overnight for evaluation by the resident team. There were no further episodes and the baby continued to appear normal, fed normally and had normal cycles of sleeping and being awake. No tests, laboratories or medications ordered. The baby was then discharged home. This was first such episode. It was thought to be unlikely to have been a seizure or related to any intercurrent illness or condition and was termed a "BRUE-" (Brief Resolved Unexplained Event). In my opinion it is most likely to have been a choking episode or an atypical breath-holding spell. Gestational age at birth- 39 weeks. Head circumference- 49 cms. Event term reported as episode of decreased responsiveness accompanied by shaking and cyanosis, event term split into decreased responsiveness, shaking and cyanosis to allow coding. Per protocol, subject received 20 mg maraviroc (1 mL) on 8/15/2017 and 25 mg maraviroc on 8/21/2017. Follow up information received 18Oct2017: Event term changed to episode of decreased responsiveness (previously decreased responsiveness accompanied by shaking and cyanosis). Shaking and cyanosis are listed as other events associated with primary AE. In my opinion it is most likely to have been a choking episode or an atypical breath-holding spell but may have been related to the immunizations received earlier that day.