A Study of Lebrikizumab (LY3650150) on Vaccine Response in Adults With Atopic Dermatitis (ADopt-VA)

Inclusion Criteria: * Chronic atopic dermatitis (AD) according to American Academy of Dermatology Consensus Criteria that has been present for ≥1 year before screening. * Eczema Area and Severity Index (EASI) score ≥16 at the baseline visit. * Investigator Global Assessment (IGA) score ≥3 (scale of 0 to 4) at the baseline visit. * ≥10% Body Surface Area (BSA) of AD involvement at the baseline visit. * History of inadequate response to treatment with topical medications; or determination that topical treatments are otherwise medically inadvisable. * Have not received any tetanus-containing vaccine within approximately 5 years of baseline. * Have never received a meningococcal conjugate vaccine or have received not more than 1 prior MCV dose at least 4 years prior to baseline, of a vaccine containing 1 or more meningococcal serogroups (serogroups A, C, W, Y). * Contraceptive use by men or women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies. * a. Female participants of childbearing potential: must agree to remain abstinent (refrain from heterosexual intercourse) or use a highly effective contraceptive method during the treatment period and for at least 18 weeks after the last dose of study drug. Women of non-childbearing potential (non-WOCBP) may participate without any contraception requirements. * b. Male participants are not required to use any contraception except in compliance with specific local government study requirements. Exclusion Criteria: * Recurring herpes simplex, herpes zoster, recurring cellulitis, chronic osteomyelitis * Evidence of active or chronic hepatitis * History of human immunodeficiency virus (HIV) infection or positive HIV serology. * Presence of skin comorbidities that may interfere with study assessments. * History of malignancy, including mycosis fungoides, within 5 years before screening, except completely treated in situ carcinoma of the cervix or completely treated and resolved non-metastatic squamous or basal cell carcinoma of the skin. * Uncontrolled chronic disease that might require bursts of oral corticosteroids, e.g., co-morbid severe uncontrolled asthma. * Have a prior history of Guillain-Barre syndrome. * Allergic to latex. * History of past vaccination allergy or Arthus-type hypersensitivity. * Have an uncontrolled seizure disorder. * Have known hypogammaglobulinemia or a screening serum immunoglobulin G (IgG) or immunoglobulin A (IgA) concentration less than the lower limit of the reporting laboratory's reference range. * Treated with topical corticosteroids (TCS), calcineurin inhibitors, or phosphodiesterase-4 inhibitors such as crisaborole within 1 week prior to the baseline visit. * Treated with the following prior to baseline visit: * a. An investigational drug within 8 weeks or within 5 half-lives (if known), whichever is longer * b. B Cell-depleting biologics, including rituximab, within 6 months * c. Other biologics within 5 half-lives (if known) or 8 weeks, whichever is longer * Received a Bacillus Calmette-Guerin (BCG) vaccination or treatment within 12 months of screening, or treated with a live (attenuated) vaccine within 12 weeks of the baseline visit or planned during the study. * A contraindication to the Tdap vaccine or mean corpuscular volume (MCV). * Pregnant or breastfeeding women, or women planning to become pregnant or breastfeed during the study.