Shigella sonnei is an emergent and highly drug resistant diarrheal pathogen.
The half-life of maternal S. sonnei IgG in infants is 43 days.
Maternal titer, antibody transfer ratio and gestational age influence birth titer.
Incidence of seroconversion in infants in southern Vietnam is 4/100 infant years.
Children should be vaccinated after 5 months of age if a candidate is licensed.