Inflammatory Challenge and Fear
Inflammatory Challenge and Fear Extinction: A Model to Enhance Understanding of Posttraumatic Stress Disorder
About This Trial
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.
Who May Be Eligible (Plain English)
Original Eligibility Criteria
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Treatments Being Tested
Typhoid VI Polysaccharide Vaccine Injectable Solution
Salmonella typhi capsular polysaccharide vaccine (Typhoid Vi Polysaccharide Vaccine): Each dose of 0.5ml Salmonella typhi capsular polysaccharide vaccine (Sanofi Pasteur, SA) is formulated to contain 25μg of purified Vi polysaccharide in a colorless isotonic phosphate buffered saline (pH 7±0.3), 4.150mg of sodium chloride, 0.065mg of disodium phosphate, 0.023mg of monosodium phosphate and 0.5ml of sterile water for injection. It is indicated for use by humans aged 2 years and older for protection against typhoid fever.
Saline Placebo (0.5mL injection)
The placebo injection will consist of 0.5mL of saline.