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Inflammatory Challenge and Fear

Inflammatory Challenge and Fear Extinction: A Model to Enhance Understanding of Posttraumatic Stress Disorder

Who can join

Ages 18 to 65 · All sexes · Healthy volunteers welcome

Inclusion Criteria:

All Subjects:

1. Aged 18-65 years old
2. Trauma Exposed
3. Current PTSD/No history of PTSD

Exclusion Criteria:

1. Contraindications to typhoid vaccine
2. Conditions associated with inflammation
3. Pregnancy or plans to become pregnant in next three months

About the study

The goal of this study is to learn if short-term changes in the immune system alter how we process information and experience fear. The main questions it aims to answer are:

Do people who receive typhoid vaccine respond differently than those who receive a placebo saline vaccine? Do people who receive typhoid vaccine experience changes in how they think and feel?

Participants will:

Attend four appointments at the San Francisco VA Health Care System;

Receive typhoid vaccine or placebo at one of the visits;

Have their physiological responding measured while listening to sounds;

Complete questionnaires and psychological tests.

What is being tested

• Typhoid VI Polysaccharide Vaccine Injectable Solution (biological)
• Saline Placebo (0.5mL injection) (other)

Sponsor: University of California, San Francisco · Participants: 288 · Started: Mar 28, 2025

Contact the study team

• Aoife O'Donovan, PhD · Phone: 415-221-4810
• Michael Srouji, BA · Phone: 415-221-4810

Official record on ClinicalTrials.gov — NCT06630884

Locations in the U.S.

Conditions

• Post-Traumatic Stress Disorder

From ClinicalTrials.gov, data retrieved Oct 2, 2026. Each study sets its own eligibility; the study team decides who can join.