Chlamydia; Vaccine exposure during pregnancy; This is a serious observational study case initially received on 20-Jun-2019, concerning a 25-year-old adult female, pregnant subject of body weight 106 lbs, height 59 inches and body mass index (BMI) 21.4, enrolled in a prospective observational safety study on pregnancy outcomes in women immunized with seasonal cell culture influenza trivalent (TIVc) or quadrivalent (QIVc) vaccine during pregnancy.  The subject's obstetrical history showed four previous pregnancies including two full-term live births and two spontaneous abortion. The subject's obstetrical history included one birth defect (reported as diaphragmatic hernia and heart murmur). The subject had no history of offspring with major congenital malformation. Also, the subject had no maternal or paternal history with major congenital malformations. The subject did not have a prior history of use of alcohol during pregnancy. The subject was a marijuana user during pregnancy (not ongoing at the time of report).  The subject's last menstrual period (LMP) date was 20-Mar-2018. The type of pregnancy was singleton. The pregnancy status was collected, and no major complications were noted. On 23-Apr-2018, the subject underwent cystic fibrosis mutation analysis and spinal muscular atrophy screening and no major congenital malformations were noted. On 04-May-2018, the subject underwent ultrasound screening and no major congenital malformations were noted. On 13-Jul-2018, the subject underwent ultrasound screening, Q natal test and maternal serum alpha-fetoprotein (MSAFP) screen, no major congenital malformations were noted.  On 11-Oct-2018, approximately at 29 weeks of gestation, the subject was administered Flu Vaccine Cell Subunit QIV NVD (batch number: 252664, dose, route of administration, anatomical location, batch number and expiry date: not reported) (explicitly coded as vaccine exposure during pregnancy) for an unknown indication.   On 05-Nov-2018, 25 days after vaccination, the subject experienced Chlamydia (infection). The subject was treated with Metrogel (metronidazole) (dose: 0.75 percent, frequency: bid, route: vaginal, start date: 05-Nov-2018 and stop date: 15-Nov-2018). On the same day, the subject underwent ultrasound screening and no major congenital malformations were noted.  On 26-Nov-2018, the subject underwent ultrasound screening and no major congenital malformations were noted.  Approximately at 39 weeks gestation, the subject gave a live birth to a male neonate by caesarean method of delivery. The characteristics of the neonate included birth weight: 3175 grams, head circumference: 35.6 cm, length: 48.3 cm and APGAR (appearance, pulse, grimace, activity, and respiration) scores were 8 at one minute and 9 at five minutes. No major congenital malformations (MCMs) were identified at birth.   The outcome of the event chlamydia was recovered on 15-Nov-2018.   The subject's estimated date of delivery (EDD) and corrected estimated date of delivery (CEDD) was reported as 25-Dec-2018.; Reporter's Comments: A 25-year-old female patient experienced chlamydia infection, 25 days post-vaccination with Flu vaccine cell subunit QIV at 29 weeks of gestation. Considering the infectious aetiology of the event and inactivated nature of the vaccine, the company assessed the causality as not related to suspect vaccine. The decision to administer a vaccine during pregnancy is related to medical decision making by the mother and her physician and is not related to any property of the medication. The event of exposure during pregnancy was assessed as not related considering the intended use of the vaccine.  The company assessed the case as serious (medically significant).