Single-Dose Cholera Vaccine in Response to an Outbreak in Zambia

Abstract

To the Editor: Killed oral cholera vaccines (OCVs) are part of the standard response package to a cholera outbreak, although the two-dose regimen of vaccines that has been prequalified by the World Health Organization (WHO) poses challenges to timely and efficient reactive vaccination campaigns. 1 Recent data suggest that the first dose alone provides short-term protection, similar to that of two doses, which may largely dictate the effect of OCVs during epidemics. [2][3][4] A cholera outbreak was detected in Lusaka, Zambia, in February 2016, after a period of 4 years without a reported case of cholera. An emergency reactive vaccination campaign was implemented in April 2016, targeting more than 500,000 persons who were at high risk for cholera in Lusaka (population, >2 million persons). The Ministry of Health, with support from Médecins sans Frontières and the WHO, decided to implement a single-dose campaign to quell the epidemic rapidly, in view of the insufficient number of vaccine doses that were available in the global stockpile to complete a two-dose campaign. In December 2016, when more doses became available, a second round of vaccination was organized and the second vaccine dose was offered to persons at risk.We conducted a matched case-control study to quantify the short-term effectiveness of a single-dose OCV regimen (Shanchol) between April 25, 2016, and June 15, 2016. The study was approved by two institutional review boards, and written informed consent was obtained from all the participants (see the Supplementary Appendix, available with the full text of this letter at NEJM.org). Cases of cholera were confirmed by means of culture, polymerase-chain-reaction as-

Recombinant vesicular stomatitis virus vector vaccines for WHO blueprint priority pathogens

“…55 Under the framework, WHO provides the vaccine to consenting at-risk individuals, health-care workers as well as ring contacts outside of clinical studies. 55,56 In a new flare-up of EVD in Guinea in March 2016, after the end of the West African epidemic was declared, the framework was utilized to vaccinate over 1500 individuals including children from the age of 6, and no EVD cases were reported in the vaccinated population. 57 Another 3481 people were vaccinated during the 9th EBOV outbreak in the DRC in May and June 2018.…”

Evaluation of the SD bioline cholera rapid diagnostic test during the 2016 cholera outbreak in Lusaka, Zambia

“…Stool samples from patients with acute non‐bloody diarrhea who presented from April 25th to June 15th 2016 to one of the treatment centres participating in the vaccine‐effectiveness study and enrolled according to inclusion criteria were included in the study. We excluded from this analysis patients enrolled after June 5th, for whom SD Bioline rapid diagnostic testing could not be carried out because of a stock out of available kits.…”

“…In a cholera outbreak that occurred in Lusaka, Zambia, from February to June 2016, the Ministry of Health (MoH) of Zambia implemented an enhanced cholera surveillance system early in the course of the outbreak using the SD Bioline Cholera Ag O1/O139 rapid test. Following an emergency reactive oral cholera vaccine (OCV) campaign, organised in April 2016 by the MoH, in collaboration with Médecins Sans Frontières, a study was implemented to estimate the vaccine effectiveness conferred by one dose of OCV . Stool specimens collected from suspected cholera cases were sent to the laboratory for confirmation by culture and PCR, in addition to the RDT.…”

Cholera control: one dose at a time

“…Qadri and colleagues' trial complements findings from other important studies on the use of a singledose OCV, which were largely secondary analyses and shorter-term prospective observational studies. 10,11 Together, the evidence shows that single-dose OCV campaigns can be effective both in the short term in outbreaks and for up to 2 years in endemic settings.…”