Safety and immunogenicity of single-dose live oral cholera vaccine CVD 103-HgR in 5-9-year-old Indonesian children.

Oral vaccines offer great promise as public-health measures to prevent disease in less-developed countries. CVD 103-HgR, a genetically engineered, attenuated, Vibrio cholerae O1 strain has proved effective in industrialised countries. We have assessed the safety, immunogenicity, and excretion of this live cholera vaccine in children in north Jakarta, Indonesia. 412 children aged 5-9 years received single doses of 5 x 10(6), 5 x 10(7), 5 x 10(8), 5 x 10(9), or 1 x 10(10) colony forming units (CFU) of CVD 103-HgR or placebo (5 x 10(8) inactivated Escherichia coli K-12) with buffer. All doses were well tolerated. The 5 x 10(8) CFU dose, which is highly immunogenic in subjects in industrialised countries (greater than 90% seroconversion), elicited seroconversions of vibriocidal antibody in only 16% of Indonesian children. By contrast, a single 5 x 10(9) CFU dose of vaccine resulted in high rates (75% and 87%) of seroconversion with two different batches of vaccine. A batch prepared with a centrifugation step gave significantly higher geometric mean titres (16-fold increase over baseline) than did a batch in which there was a filtration step between fermentation and lyophilisation (10-fold increase over baseline). At a 5 x 10(9) CFU dose, CVD 103-HgR is well tolerated and highly immunogenic in Indonesian children and should therefore be further investigated for use as a one-dose live oral cholera vaccine in developing countries.

PIP: In February-March 1990, health workers administered a single dose of the oral cholera CVD 103 HgR vaccine with 5 x 100 million colony forming units (CFU), 5 x 10 million CFU, or 5 x 1 million CFU or of a placebo to 274 5-9 year old children in a village within the catchment area of the Infectious Diseases Hospital in North Jakarta, Indonesia. In September-October 1990, they gave a dose of the same vaccine containing either 5 x 1 billion CFU or 1 x 10 billion CFU from 1 of 2 different batches or a placebo (5 x 100 million inactivated Escherichia coli K 12) to 140 5-9 year old children. 70 children also received an extra dose of buffer. They conducted these trials to examine the safety, immunogenicity, and excretion of this live cholera vaccine. The higher dose genetically engineered oral cholera vaccine (5 x 1 billion CFU) resulted in higher seroconversion rates than the 5 x 100 million CFU vaccine which has 90% seroconversion rates among North American and European children (16% vs. 75-87% for 2 different batches). The centrifuged prepared vaccine resulted in significantly greater geometric mean titers (16-fold rise over baseline) than did the filtered prepared vaccine (10-fold rise over baseline) (p=.001). The extra buffer did not improve immunogenicity of CVD 10 HgR in these children. None of the 124 children who took the 5 x 1 billion or 1 x 10 billion CFU dose excreted the attenuated strain of Vibrio cholerae 01. Thus this recombinant vaccine strain would unlikely enter the environment or b transmitted to others. The frequency of adverse reactions was basically the same for the vaccine and the placebo. These results showed that the Indonesian children tolerated a single 5 x 1 billion dose of CVD 103 HgR well and induced considerable immunogenicity. Future studies using the same dose in 2-4 year old children are planned.

Oral immunisation against typhoid fever in Indonesia with Ty21a vaccine.

When tested under conditions of moderate transmission of typhoid fever, a liquid formulation of the oral typhoid fever vaccine Ty21a had a protective efficacy of 96% in Egypt, and an enteric coated capsule formulation had an efficacy of 67% in Chile. We compared the two formulations under conditions of intense transmission of typhoid fever in Indonesia in a randomised, double-blind trial. 20,543 subjects (age range 3-44 years) received either three doses of enteric coated capsules containing placebo or live Ty21a, or three doses of lyophilised placebo or live Ty21a reconstituted with phosphate buffer. During 30 months of follow-up, the rate of blood-culture-positive typhoid fever among controls was 810/100,000 per year. Rates of typhoid fever were 379/100,000 per year for subjects who received the liquid formulation of vaccine and 468/100,000 per year for subjects who received enteric coated capsules. The protective efficacies of the liquid and enteric coated formulations were 53% and 42%, respectively. Neither formulation protected against infection with Salmonella paratyphi A. No major side-effects were noted, but the overall incidence of side-effects was greater in the vaccine groups. Under conditions of intense transmission, Ty21a protected against typhoid fever; however, because Ty21a will not protect all individuals, there is a need for additional approaches to prevent the disease.

PIP: When tested under conditions of moderate transmission of typhoid fever, a liquid formulation of the oral typhoid fever vaccine, Ty21a, had a protective efficacy of 96% in Egypt, and an enteric coated capsule formulation had an efficacy of 67% in Chile. The authors compared the 2 formulations under conditions of intense transmission of typhoid fever in Indonesia in a randomized, double blind trial. 20,543 subjects (age range 3-44 years) received either 3 doses of enteric-coated capsules containing placebo or live Ty21a, or 3 doses of lyophilized placebo or live Ty21a reconstituted with phosphate buffer. During 30 months of followup, the rate of blood-culture-positive typhoid fever among controls was 810/100,000/year. Rates of typhoid fever were 379/100,000/year for subjects who received the liquid formulation of vaccine and 468/100,000/year for subjects who received enteric coated capsules. The protective efficacies of the liquid and enteric coated formulations were 53% and 42%, respectively. Neither formulation protected against infection with Salmonella paratyphi A. No major side effects were noted, but the overall incidence of side effects was greater in the vaccine groups. Under conditions of intense transmission, Ty21a protected against typhoid fever; however since it will not protect all individuals, there is a need for additional approaches in prevention of the disease.