Live Shigella flexneri 2a and Shigella sonnei I vaccine candidate strains with two attenuating markers. II, Preliminary results of vaccination of adult volunteers and children aged 2-17 years

Abstract Shigella flexneri 2a and Shigella sonnei I vaccine candidate strains were tested for tolerance in 14 adults as well as for tolerance and immunogenicity in children aged 2–17 years. For fresh culture material, the limit for side effects fading within 36 h such as meteorism, loose stools, tenesmus and slight temperature, and tolerated by volunteers was 3 × 10 9 colony-forming units (c.f.u.). Excretion of vaccine strain germs for 2–3 days was observed only at doses of 10 10 c.f.u. and greater (2–3 × 10 10 ). Children tolerated up to the maximum dose of 1–3 × 10 9 c.f.u. of the lyophlized vaccine without side effects. No vaccine strain germs were found in faeces, antigen being detected for 4–5 days. The total dose of 1–3 × 10 9 c.f.u. being distributed among three oral inoculations at intervals of 1–2 days induced coproantibodies in 70% of the vaccinees during the first 3 months, and in 30–40% up to 6 months. In contrast, the single application of this total dose for primary immunization, or booster after 10 months, proved to be more efficient. Ninety per cent of the subjects had markedly elevated titres for not less than 6 months.