Use of oral cholera vaccines in an outbreak in Vietnam: a case control study.

Abstract

BACKGROUND:

Killed oral cholera vaccines (OCVs) are available but not used routinely for cholera control except in Vietnam, which produces its own vaccine. In 2007-2008, unprecedented cholera outbreaks occurred in the capital, Hanoi, prompting immunization in two districts. In an outbreak investigation, we assessed the effectiveness of killed OCV use after a cholera outbreak began.

METHODOLOGY/PRINCIPAL FINDINGS:

From 16 to 28 January 2008, vaccination campaigns with the Vietnamese killed OCV were held in two districts of Hanoi. No cholera cases were detected from 5 February to 4 March 2008, after which cases were again identified. Beginning 8 April 2008, residents of four districts of Hanoi admitted to one of five hospitals for acute diarrhea with onset after 5 March 2008 were recruited for a matched, hospital-based, case-control outbreak investigation. Cases were matched by hospital, admission date, district, gender, and age to controls admitted for non-diarrheal conditions. Subjects from the two vaccinated districts were evaluated to determine vaccine effectiveness. 54 case-control pairs from the vaccinated districts were included in the analysis. There were 8 (15%) and 16 (30%) vaccine recipients among cases and controls, respectively. The vaccine was 76% protective against cholera in this setting (95% CI 5% to 94%, P = 0.042) after adjusting for intake of dog meat or raw vegetables and not drinking boiled or bottled water most of the time.

CONCLUSIONS/SIGNIFICANCE:

This is the first study to explore the effectiveness of the reactive use of killed OCVs during a cholera outbreak. Our findings suggest that killed OCVs may have a role in controlling cholera outbreaks.

• Authors: Dang Duc Anh, Anna Lena Lopez, Vu Dinh Thiem, Shannon L Grahek, Tran Nhu Duong, Jin Kyung Park, Hye Jung Kwon, Michael Favorov, Nguyen Tran Hien, John D Clemens
• Journal: PLoS neglected tropical diseases (PLoS Negl Trop Dis) Vol. 5 Issue 1 Pg. e1006 (Jan 25 2011) ISSN: 1935-2735 [Electronic] United States
• PMID: 21283616 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Cholera Vaccines
• Vaccines, Inactivated

Topics

• Adolescent
• Adult
• Aged
• Aged, 80 and over
• Case-Control Studies
• Cholera (epidemiology, prevention & control)
• Cholera Vaccines (administration & dosage, immunology)
• Disease Outbreaks
• Female
• Humans
• Male
• Middle Aged
• Vaccines, Inactivated (administration & dosage, immunology)
• Vietnam (epidemiology)
• Young Adult