ACNS American Clinical Neurophysiology Society EEG amplitude-integrated EEGBCG bacille Calmette-Guérinc EEG conventional EEG EEG electro encephalography GA gestational age HBW high birth weight (≥4000 g) ILAE International League Against Epilepsy LBW low birth weight (≥1500–2499 g) MRI Magnetic Resonance Imaging NBW normal birth weight (≥2500–3999 g)NICU neonatal intensive care unit PMA post menstrual age Tdaptetanus-diphtheria-acellular pertussis Tptetanus-diphtheria-acellular pertussis VLBW very low birth weight (<1500 g)WHO World Health Organization
1.1. Need for developing case definitions and guidelines for data collection, analysis, and presentation for neonatal seizures as an adverse event following immunization
Seizures are the most common neurological emergency in newborns and can be associated with significant mortality and neuro-developmental disability. Neonatal seizures are a major challenge for clinicians because of inconspicuous clinical presentation, variable electro-clinical correlation, and poor response to antiseizure drugs. It is well recognized that fever and infection can trigger seizures in young children and that this risk is enhanced in children with epilepsy. As immunization may cause a fever, vaccination can be a non-specific trigger for seizures in children . On the other hand, children with epilepsy do not appear to be at increased risk of seizures following immunization . It is unclear whether vaccination in newborns or maternal vaccination, is associated with a higher risk of neonatal seizures. However, as maternal immunization with established vaccines becomes more prevalent across multiple geographies, and new maternal vaccine candidates enter late-stage development, it is becoming increasingly important to create easily adopted standard definitions for adverse events potentially associated with these interventions. The Brighton Collaboration has previously published a case definition for seizures in children  but not for seizures in neonates.
1.1.1. Epidemiology of neonatal seizures
The reported prevalence and incidence of neonatal seizures vary considerably due to differences in study methodology, especially in the identification of neonatal seizures, and geographic setting , . The majority of seizures in neonates present without clinical signs ,  and can be recognized only with cEEG (conventional electroencephalography) monitoring, which has not been used in all studies. Therefore, the exact incidence of electrographic, clinically silent neonatal seizures in term and preterm babies is not known (Table 1, Table 2).