Shigella are gram-negative bacteria that cause severe diarrhea and dysentery. In 2013, the infection caused about 34,400 deaths in children less than 5 years old. Transmission usually occurs by contaminated food and water or through person-to-person contact. Various immune mechanisms show potential for durable and protective mucosal response, according to research. The bioconjugate S. flexneri 2a vaccine is off to a good start, according to the American Society for Microbiology (ASM), due to its promise of clinical tolerability, strong immunogenicity, and the potential for efficient, low-cost manufacturing.