Open Label Study to Assess the ~32-Year Persistence of Hepatitis A Antibody Among Participants in the Pivotal, Double-Blind, Placebo-Controlled Efficacy Study of VAQTA (Study 023-001)

Study 023-Persistence

The goal of this clinical trial is to evaluate the persistence of Hepatitis A antibody \~32 years post vaccination in healthy adults. The questions this study will answer are: 1) how long antibody persists and 2) The immune response to an additional dose of vaccine among those with no detectable antibody. Participants will be asked to provide a blood specimen. Those with no detectable antibody will be offered an additional dose of vaccine. The kinetics of antibody response in this population will be summarized.

2024-01-01

2025-03-01

2025-06-01

Not yet recruiting

Early phase I

300

Inclusion Criteria: * Consent obtained * Participated in original hepatitis A study in 1991 * No detectable hepatitis A antibody \~32 years after study start Exclusion Criteria: * Receipt of any dose of hepatitis A vaccine other than the hepatitis A vaccine used in the initial studies * History of hepatitis A * Receipt of blood transfusion or blood products, including immunoglobulins, within the past 6 months. * Receipt of any vaccine within the 14 days before receipt of the additional dose of hepatitis A vaccine or scheduled to receive any vaccine within 30 days after receipt of a booster dose of vaccine.

{'studyType': 'INTERVENTIONAL', 'phases': ['PHASE4'], 'designInfo': {'allocation': 'NA', 'interventionModel': 'SINGLE_GROUP', 'primaryPurpose': 'BASIC_SCIENCE', 'maskingInfo': {'masking': 'NONE'}}, 'enrollmentInfo': {'count': 300, 'type': 'ESTIMATED'}}

2023-12-28