Bacterial vaginosis; Vaccine exposure during pregnancy; This is a spontaneous case, initially received from other health professional on 08-Oct-2019, concerning a 17-year-old, pregnant, female patient, of body weight: 123 lbs, height: 66 inches and body mass index (BMI): 19.9.  The patient's medical history included chlamydial and yeast infection, anaemia, and the patient was positive on group B Streptococcus. The patient's past medication included azithromycin used for chlamydia, while the concomitant medications included Prenatal vitamins (unspecified minerals and vitamins) for pregnancy and ferrous sulphate for anaemia.    The patient had no previous pregnancies. The patient had no history of offspring with major congenital malformation (MCM). The patient had no maternal or paternal history with MCMs. The patient did not have a prior history of use of tobacco, alcohol or illicit drugs during pregnancy. The paternal age was 19.  The patient's last menstrual period (LMP) date was 07-Apr-2018. The type of pregnancy was singleton. The patient's estimated delivery date (EDD) was reported as 12-Jan-2019 and corrected EDD (CEDD) was not reported.  On 30-Jul-2018, cystic fibrosis analysis and spinal muscular atrophy test were performed, and no MCM was noted.   On 02-Aug-2018, ultrasound, alpha fetoprotein and quad screen were performed, and no MCMs were noted.   On 19-Aug-2018, the ultrasound was performed, and no MCM was noted.  On 25-Oct-2018, at approximately 29 weeks of gestation, the patient received Flucelvax QIVc [influenza vaccine, subunit influenza virus vaccine polyvalent; batch number: 252664, dose, route of administration, anatomical location and expiry date: not reported] (explicitly coded as Vaccine exposure during pregnancy') for an unknown indication.  On 24-Dec-2018, 1 month and 29 days after vaccination, the patient developed bacterial vaginosis.  On 03-Jan-2019, ultrasound was performed, and no MCMs were noted.   On 04-Jan-2019, the patient recovered from the event of bacterial vaginosis.  At 39.7 weeks of gestation, the patient vaginally delivered live male neonate. Neonate's birth weight was 3402 grams, body length was 50.8 cm, and head circumference was 31.8 cm. The appearance, pulse, grimace, activity and respiration (APGAR) scores were 9 (one minute), 9 (five minutes) and for ten minutes was not reported. There was no MCM identified at birth.   The case was assessed as non-serious.  The reporter did not provide causality assessment.  Significant case correction performed on 22-Nov-2019: Report type changed from 'report from study' to 'spontaneous', therefore, the suspect product recoded from study drug to Flucelvax QIV; dose and indication removed. Narrative amended accordingly.  Company comment: The patient experienced bacterial vaginosis 1 month and 29 days, after vaccination after vaccination with the suspect product Flucelvax QIVc. Reportedly, vaccination occurred during pregnancy. Chronology is plausible. Pregnant state may provide alternative aetiology for the event and medical history of chlamydial infection and yeast infection may have contributed to development of the event. Causal relationship between the suspect product and exposure during pregnancy is assessed as not related per company conventions. For the event bacterial vaginosis, causal role of the suspect product is assessed as unlikely related.; Sender's Comments: The patient experienced bacterial vaginosis 1 month and 29 days, after vaccination after vaccination with the suspect product Flucelvax QIVc. Reportedly, vaccination occurred during pregnancy. Chronology is plausible. Pregnant state may provide alternative aetiology for the event and medical history of chlamydial infection and yeast infection may have contributed to development of the event. Causal relationship between the suspect product and exposure during pregnancy is assessed as not related per company conventions. For the event bacterial vaginosis, causal role of the suspect product is assessed as unlikely related.