Suspected vaccination failure; Haemophilus influenzae type B (Hib) Bacterimia; fever; This case was reported in a literature article and described the occurrence of suspected vaccination failure in a 8-month-old patient who received Haemophilus influenzae type b vaccine for prophylaxis.   Co-suspect products included Haemophilus influenzae type b vaccine (batch number UNK, expiry date unknown) for prophylaxis and Haemophilus influenzae type b vaccine (batch number UNK, expiry date unknown) for prophylaxis.   The subject's past medical history included premature baby (born at 33-week). Concomitant products included PNEUMOCOCCAL CONJUGATE VACCINE.   On an unknown date, the patient received the 1st dose of Haemophilus influenzae type b vaccine, the 2nd dose of Haemophilus influenzae type b vaccine and the 3rd dose of Haemophilus influenzae type b vaccine. On an unknown date, less than 9 months after receiving Haemophilus influenzae type b vaccine, Haemophilus influenzae type b vaccine and Haemophilus influenzae type b vaccine, the patient experienced vaccination failure (serious criteria hospitalization and GSK medically significant), hemophilus bacteremia (serious criteria hospitalization and GSK medically significant) and fever (serious criteria hospitalization). On an unknown date, the outcome of the vaccination failure, hemophilus bacteremia and fever were unknown.   The reporter considered the vaccination failure, hemophilus bacteremia and fever to be related to Haemophilus influenzae type b vaccine, Haemophilus influenzae type b vaccine and Haemophilus influenzae type b vaccine.  Additional details were provided as follows: This case was reported in a literature article and described suspected vaccination failure, in a patient aged 8-month-old of unspecified gender, who was vaccinated with, who was vaccinated with Unspecified Haemophilus influenzae type B (Hib) vaccine (manufacturer unknown) for prophylaxis.   The patient was a part of retrospective cohort study that aimed to determine the association between bacteremia and vaccination status in children presenting to a pediatric emergency department. The study included children aged 2-36 months with blood cultures obtained in the pediatric emergency department between 1st January 2013 and 31st December 2017. The exposure of interest was immunization status, defined as number of Haemophilus influenzae type B (Hib) and Streptococcus pneumoniae vaccinations, and the main outcome positive blood culture. [In this study, Children aged 2-36 months with blood cultures obtained in the ED were eligible for inclusion. 2 months was chosen as the lower age limit due to an institutional febrile neonate guideline addressing the care of infants up to 60 days of life and 36 months as our upper age limit to maintain consistency with previous fever without source studies]. The patient was a 33-week premature baby. The patient did not have any high-risk medical condition which could increase the risk of bacteremia. No information on patient medical or family history or concurrent condition or concomitant medication was reported.   On an unknown date, the patient received 3 sets of Unspecified Hib vaccine (administration site or route unspecified, dose not reported, batch number not provided) and unspecified Pneumococcal vaccine. The age at vaccination was not reported. [In this study, children older than 7 months of age were considered under vaccinated if they had received fewer than 3 sets of vaccines. Patients were grouped according to the number of PCV and Hib vaccinations received].  On an unknown date between 1st January 2013 and 31st December 2017, an unknown period after vaccination, the patient experienced fever. The patient presented to pediatric emergency department and blood culture was obtained.  The site of infection was blood and the patient was diagnosed with Hib type B bacteremia. On an unspecified date, the patient was discharged. [In this study, Ill appearance was defined as documentation of "ill-appearing," "toxic-appearing," poor perfusion including capillary refill time more than 3 seconds, or respiratory distress]. The case was considered for suspected vaccination failure being time to onset unknown. The case was considered as serious due to suspected vaccination failure and hospitalization. Treatment was not reported. Outcome of the event was not reported.  The authors commented "In this retrospective cohort study of 4742 blood cultures obtained from children in the pediatric ED, we found that vaccination status was not associated with bacteremia. Our cohort is composed of children cared for at a pediatric quaternary care facility. All of the cases of S pneumoniae and Hib bacteremia in this study were isolated from subjects who were fully vaccinated. In this study, 5.0% of blood cultures were contaminated and younger infants were significantly more likely to have contaminant growth, likely owing to the greater number of overall cultures obtained. In a systematic review of children presenting with fever without a source, the rate of contaminant growth exceeded that of pathogenic growth in all subjects. Vaccination against S pneumoniae and H influenza has virtually eliminated these pathogens in children aged 2-36 months. Obtaining blood cultures based on vaccination status may not be routinely indicated unless these specific pathogens are of high clinical suspicion or in populations that may lack herd immunity due to low rates of vaccination. In the age of routine vaccinations against S pneumoniae and Hib, clinicians require further guidance on specifically when blood cultures are indicated in pediatric patients younger than the age of 3 years".