Safety Analysis of Typhoid Vaccines: A Retrospective Study Using VAERS Data

Bin Niu ¹ Dongdong Xie ¹ Kangqiang Weng ¹ Hu Li ¹ Xiang Wu ¹ Linlu She ¹ Yingbo Dai ^1* ruoyun Xie ^2*

• ¹ The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, Guangdong Province, China
• ² Department of Urology, Fujian Medical University Union Hospital, 29 Xinquan Road, Gulou District, Fuzhou, Fujian Province, Fuzhou, China

Background: Typhoid vaccination is a key strategy for controlling typhoid disease, but vaccine safety remains a major challenge. The purpose of this study was to evaluate the safety of typhoid vaccines by analyzing adverse events (AEs) obtained from major pharmacovigilance databases, including Vaccine Adverse Event Reporting System (VAERS).We analyzed the VAERS from January 2000 through December 2024 to identify typhoid vaccine safety signals and age variations. Using disproportionality (PRR, ROR) and regression models, we assessed how demographic factors influence adverse event occurrence.Results: A total of 8,393 AEs were analyzed. The overall incidence of serious adverse reactions was 15.2%, consistent across age groups. The onset of most AES is within a day of vaccination, and the onset is faster in younger people. The ratio of reports reveals signals of serious aes, such as "chills" and "myalgia," while non-serious events such as "diarrhea" and "hives" are reported at higher rates.This study provides a comprehensive assessment of typhoid vaccine safety, highlighting both common and rare AEs. The identification of severe reactions underscores the need for continued pharmacovigilance. These findings provide valuable information for vaccine safety monitoring and the development of tailored vaccination strategies, especially in high-risk populations.