Persistence of immunity and seroprotection 4 years after a primary vaccination schedule with a Hansenula polymorpha recombinant hepatitis B vaccine

To evaluate the persistence of the immune response in a population of healthy volunteers that had been vaccinated with a new Hansenula polymorpha recombinant hepatitis B vaccine in a previous clinical study 4 years before, we measured the titre of anti-HBs. All, but one of the evaluated volunteers remained protected. None of them had experienced any adverse event related to the vaccine from the moment of immunization, to the present. The vaccine proved to be immunogenic and to confer long-term protection in this group.

A cost-benefit analysis of programmatic use of CVD 103-HgR live oral cholera vaccine in a high-risk population

BACKGROUND

Cholera spread to Latin America in 1991; subsequently, cholera vaccination was considered as an interim intervention until long-term solutions involving improved water supplies and sanitation could be introduced. Three successive summer cholera outbreaks in northern Argentina and the licensing of the new single-dose oral cholera vaccine, CVD 103-HgR, raised questions of the cost and benefit of using this new vaccine.

METHODS

This study explored the potential benefits to the Argentine Ministry of Health of treatment costs averted, versus the costs of vaccination with CVD 103-HgR in the relatively confined population of northern Argentina affected by the cholera outbreaks. Water supplies and sanitation in this area are poor but a credible infrastructure for vaccine delivery exists.

RESULTS

In our cost-benefit model of a 3-year period (1992-1994) with an annual incidence of 2.5 case-patients per 1000 population and assumptions of vaccine efficacy of 75% and coverage of 75%, vaccination of targeted high risk groups would prevent 1265 cases.

CONCLUSION

Assuming a cost of US$602 per treated case and of US$1.50 per dose of vaccine, the total discounted savings from use of vaccine in the targeted groups would be US$132,100. The projected savings would be altered less by vaccine coverage (range 75-90%) or efficacy (60-85%) changes than by disease incidence changes. Our analysis underestimated the true costs of cholera in Argentina because we included only medical expenditures; Indirect losses to trade and tourism had the greatest economic impact. However, vaccination with CVD 103-HgR was still cost-beneficial in the base case.

Health advice for travelers to Latin America

Practical and precise information about the potential infectious health hazards that travelers to Latin America may encounter is reviewed in this article. Some diseases are briefly described, others are only mentioned. The countries have been grouped into four geographical areas following the classification of the World Health Organization. The discussion on each area includes information on travelers' diarrhea, malaria, cholera, typhoid fever, yellow fever, and other diseases or special problems.