Inclusion Criteria:  Age 12 years and above. Subject able and willing to self-administer tralokinumab with Device A. Diagnosis of AD as defined by the Hanifin and Rajka (1980) criteria for AD. History of AD for ≥1 year. A recent history (within 1 year before the screening visit) of inadequate response to treatment with topical medication or for whom topical treatments are otherwise medically inadvisable. AD involvement of ≥10% body surface area at screening and baseline. An EASI score of ≥12 at screening and ≥16 at baseline. An IGA score of ≥3 at screening and at baseline. Applied a stable dose of emollient twice daily (or more, as needed) for at least 14 days before baseline.  Exclusion Criteria:  Active dermatologic conditions that may confound the diagnosis of AD or would interfere with assessment of treatment. Use of tanning beds or phototherapy within 4 weeks prior to baseline. Treatment with systemic immunosuppressive/immunomodulating drugs and/or systemic corticosteroids within 4 weeks prior to baseline. Treatment with topical corticosteroids, topical calcineurin inhibitors, topical phosphodiesterase 4 inhibitors, or topical Janus kinase inhibitors within 2 weeks prior to baseline. Receipt of any marketed biological therapy (i.e. immunoglobulin, anti immunoglobulin E) including dupilumab or investigational biologic agents 3 to 6 months prior to baseline. Active skin infections within 1 week prior to baseline. Clinically significant infection within 4 weeks prior to baseline. A helminth parasitic infection within 6 months prior to the date informed consent is obtained. Tuberculosis requiring treatment within 12 months prior to screening. Known primary immunodeficiency disorder.