Attention deficit hyperactivity disorder; Herpes simplex; Vaccine exposure during pregnancy; This is a serious observational study case, initially received from other health professional on 18-Jun-2019, concerning a 28-year-old adult female pregnant subject of body weight: 211.2 lbs, height: 63 inches and body mass index (BMI) 37.4, enrolled in prospective observational safety study on pregnancy outcomes in women immunized with Afluria QIV, a seasonal quadrivalent vaccine, during pregnancy.  The subject had 4 previous pregnancies in which one was full term live birth with no reported birth defects and three were spontaneous abortions. The subject did not have a history of offspring with major congenital malformation. On an unknown date, the subject's family history of major congenital malformation was collected, and the subject had no maternal or paternal history with major congenital malformations.   The subject's current condition included seizures. The subject's concomitant medication included Multivitamin (ascorbic acid, chromium, copper, folic acid, inositol, magnesium, manganese, nicotinamide, pantothenic acid, potassium, pyridoxine hydrochloride, retinol, riboflavin, selenium, vitamin b1 nos, vitamin b12 nos, vitamin e nos, zinc) as a supplement and folic acid for seizures.   The subject's last menstrual period date (LMP) was 22-Sep-2018. The type of pregnancy was singleton. The subject did not use tobacco, alcohol or illicit drugs during pregnancy. On an unknown date, pregnancy status of the subject was collected, and no pregnancy complications were noted.  On 07-Nov-2018, the subject underwent ultrasound and no major congenital malformation was noted.   On 26-Nov-2018, at approximately 9 weeks of gestation, the pregnant subject was administered Flu Vaccine Egg Split QIV CSL [influenza vaccine, batch number: K5F5R (as reported), dose, route of administration, expiry date and anatomical location: not reported] (explicitly coded as vaccine exposure during pregnancy) for an unknown indication.   On 14-Dec-2018, the subject underwent Nuchal translucency test and Sequential 1 (prenatal test) and no major congenital malformations were noted.  On 11-Jan-2019, the subject underwent Sequential 2 (prenatal test) and no major congenital malformation was noted.  On an unknown date, the subject developed herpes simplex and attention deficit hyperactivity disorder (ADHD). The subject was treated with Vyvanse (lisdexamfetamine mesilate, dosage: 40 mg, qd, orally, from 30-Apr-2019 and ongoing) for ADHD and Valtrex (valaciclovir hydrochloride, dosage: 500 mg, qd, orally from 28-May-2019 and ongoing) for herpes simplex.  The outcome of the events was not recovered.  The subject's corrected estimated delivery date (CEDD) was reported as 29-Jun-2019 and estimated delivery date (EDD) was reported as 30-Jun-2019.; Reporter's Comments: A 28-year-old pregnant subject with concurrent medical condition seizures experienced herpes simplex infection and attention deficit hyperactivity disorder (ADHD), unspecified period after receipt of Flu Vaccine Egg Split (considered as vaccine exposure during pregnancy). Despite lack of onset latency, the event Herpes simplex infection assessed as not related to inactivated suspect vaccine considering the infectious aetiology (Herpes simplex virus). The event ADHD lack onset latency, hence causality assessed as unassessable. The concurrent medical condition seizures is considered as known risk factor for ADHD. The case will be further assessed upon receipt of follow-up information. The event vaccine exposure during pregnancy assessed as not related considering the intended use of vaccine. The company assessed this case as serious (medically significant).