A Study to Learn How Well Dupilumab Works in Adult and Adolescent Participants With Eosinophilic Gastritis With or Without Eosinophilic Duodenitis and the Side Effects it May Have

Icahn School of Medicine at Mount Sinai (ISMMS) - The Mount Sinai Hospital (MSH), New York

Northwell Health, Great Neck

University of Pennsylvania, Philadelphia

Humanitas Research Hospital, Rozzano

Fondazione Serena Onlus - Azienda Ospedaliera Niguarda Ca' Granda - Centro Clinico Nemo (Neuro Muscular Omnicentre), Milan

University of North Carolina at Chapel Hill, Chapel Hill

Duke University, Durham

Charlotte Gastroenterology & Hepatology, PLLC, Charlotte

ESI Medical Research, PLLC, Kinston

Encore Borland-Groover Clinical Research, Jacksonville

Ohio State University Medical Center, Columbus

University of Cincinnati Medical Center-Children's Hospital Medical Center, Cincinnati

University of Michigan, Ann Arbor

Froedtert Hospital, Milwaukee

MNGI Digestive Health P.A., Plymouth

Mayo Clinic Hospital Rochester, Rochester

Azienda Ospedaliero Universitaria Pisana, Pisa

Northwestern University, Chicago

University Of Kansas, Kansas City

U.O. Di Ematologia-Azienda Policlinico Consorziale, Ospedaliero-Universitaria, Ospedale, Bari

Allergy, Asthma and Clinical Research Center, Oklahoma City

TDDC dba GI Alliance Research, Mansfield

University of Colorado Anschutz Health Science Building (AHSB) CU Research Pharmacy, Aurora

University of Utah, Salt Lake City

Phoenix Childrens Hospital, Phoenix

Advanced Research Institute, Reno

University of California - Los Angeles (UCLA), Los Angeles

University of Southern California Keck School of Medicine, Los Angeles

GastroIntestinal BioSciences, Los Angeles

AOOR Villa Sofia/Cervello, Palermo

Scripps Clinic, La Jolla

Om Research LLC, Apple Valley

United Medical Doctors, Murrieta

Om Research LLC, Lancaster

Ucsf Medical Center (Benioff Childrens Hospital), San Francisco

The Oregon Clinic - Gastroenterology East, Portland

Seattle Children's Home Health Company, Seattle

Connecticut Clinical Research Institute, Bristol

UConn Health, Farmington

Beth Israel Deaconess Medical Center (BIDMC) Harvard Medical School, Boston

Dartmouth Hitchcock Medical Center, Lebanon

Stollery Children's Hospital - University of Alberta, Edmonton

Ospedale S Giovanni Calibita Fatebenefratelli Isola Tiberina, Roma

University of Rome - Pediatric Gastroenterology and Liver Unit, Rome

Iizuka Hospital, Iizuka

Ogaki Municipal Hospital, Ōgaki

Kure Kyosai Hospital, Kure

Hyogo Prefectural Harima-Himeji General Medical Center, Himeji

Kobe University Graduate School of Medicine, Kobe

Yokohama City University Hospital, Yokohama

Kawasaki Medical School Hospital, Kurashiki

Toranomon Hospital, Minato-ku

Yamagata University Hospital, Yamagata