An adverse event (AE) is any untoward medical occurrence in a clinical study subject administered a medicinal product, it does not necessarily have a causal relationship with the treatment. An AE can therefore be any unfavorable and unintended sign (including an abnormal finding), symptom, or disease temporally associated with the use of a medicinal (investigational or non-investigational) product, whether or not related to that medicinal product. Unsolicited adverse events were events which were reported by the participant voluntarily or obtained by means of interviewing the participant in a nondirected manner at study visits.

A serious adverse event (SAE) is an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly.

The following neuroinflammatory disorders were considered immediate reportable events and which had to be reported to the sponsor within 24 hours of becoming aware of the event. Neuroinflammatory disorders included: cranial nerve disorders including paralyses/paresis (example: bell's palsy), optic neuritis, multiple sclerosis, transverse myelitis, guillain-barre syndrome including miller fisher syndrome, bickerstaff's encephalitis and other variants, acute disseminated encephalomyelitis, including site-specific variants (example: non-infectious encephalitis, encephalomyelitis, myelitis, myeloradiculomyelitis), myasthenia gravis and lambert-eaton myasthenic syndrome, immune-mediated peripheral neuropathies and plexopathies, including chronic inflammatory, demyelinating polyneuropathy, multifocal motor neuropathy, and polyneuropathies associated with monoclonal gammopathy, narcolepsy, isolated paresthesia of more than 7 days duration.

An AE was any untoward medical occurrence in a clinical study participant administered a medicinal (investigational or non-investigational) product. Solicited local AEs were pre-defined local (at the injection site) AEs for which participants were specifically questioned and which were noted by participants in their diary for 7 days post first vaccination. Solicited local AEs were: injection site pain/tenderness, erythema, induration/swelling, itching at the vaccination site.

An AE was any untoward medical occurrence in a clinical study participant administered a medicinal (investigational or non-investigational) product. Participants were instructed on how to note signs and symptoms in the diary on a daily basis for 7 days post-vaccination (Day of vaccination and the subsequent 7 days) for solicited systemic AEs. Solicited systemic events included fever, headache, fatigue/malaise, myalgia, nausea/vomiting, arthralgia and chills.