This study is exploring how short-term changes in your immune system might affect how you process information and experience fear, especially if you have Posttraumatic Stress Disorder (PTSD). Researchers want to see if receiving the Typhoid Vi Polysaccharide Vaccine, which can cause a temporary immune response, changes how people think and feel compared to those who receive a saline placebo (an inactive injection). They will measure your skin conductance response (how much your skin conducts electricity, which can indicate emotional arousal) to understand these changes. You might be able to join if you are 18-60 years old, have experienced trauma, and currently have PTSD or no history of PTSD. The study aims to enroll 288 participants.

Study design

This is an interventional study planning to enroll 288 participants. It compares the effects of the Typhoid Vi Polysaccharide Vaccine to a saline placebo.

What's involved

You will attend four appointments at the San Francisco VA Health Care System. During one visit, you will receive either the vaccine or placebo, have your physiological responses measured while listening to sounds, and complete questionnaires and psychological tests.

Compensation

Not stated in the trial record.

Follow-up

Your skin conductance response will be assessed at baseline, 4.5 hours, and one week after receiving the vaccine or placebo.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.