Oral Cholera Vaccine Campaign Research Articles

Navigating water crisis, cholera, and refugee context: Lessons from Nakivale refugee settlement, Isingiro District, Uganda.

Inadequate safe water supply and cholera outbreaks are significant contributors to ill health in displaced populations, exacerbating the vulnerability of refugees fleeing conflicts. In November 2021, the Nakivale Refugee Settlement faced a cholera outbreak and water scarcity, putting displaced persons at risk of ill health. This study aimed to investigate the lessons learned from this incident and identify pathways to prevent future outbreaks, ultimately safeguarding the lives and well-being of vulnerable populations. A descriptive cross-sectional study analysed epidemiological data from the Uganda Ministry of Health, investigating the cholera outbreak among refugees in Nakivale Refugee Settlement, Isingiro district, from November 3rd to December 2nd, 2021. The outbreak affected 173 refugees, primarily in Nyarugugu B and C villages, with consumption of contaminated lake water identified as the likely cause. Inadequate access to clean water and sanitation facilities exacerbated the outbreak, which disproportionately affected individuals aged 10-19 years (30.1%) and females (65%). Promotion of safe water, sanitation, and oral cholera vaccination campaigns effectively controlled the outbreak. This study highlights the critical importance of providing refugees with access to safe water and sanitation infrastructure to prevent cholera outbreaks. Timely implementation of oral cholera vaccination campaigns and enhanced water management systems are crucial to preventing future outbreaks in refugee settlements.

The Costs and Cost-Effectiveness of a Two-Dose Oral Cholera Vaccination Campaign: A Case Study in a Refugee Camp Setting in Thailand.

Oral cholera vaccination (OCV) campaigns are increasingly used to prevent cholera outbreaks; however, little is known about their cost-effectiveness in refugee camps. We conducted a cost-effectiveness analysis of a pre-emptive OCV campaign in the Maela refugee camp in Thailand, where outbreaks occurred with an annual incidence rate (IR) of up to 10.7 cases per 1000. Data were collected via health sector records and interviews and household interviews. In the base-case scenario comparing the OCV campaign with no campaign, we estimated the campaign effect on the cholera IR and case fatality rate (CFR: 0.09%) from a static cohort model and calculated incremental cost-effectiveness ratios for the outcomes of death, disability-adjusted life-years (DALYs), and cases averted. In sensitivity analyses, we varied the CFR and IR. The household economic cost of illness was USD 21, and the health sector economic cost of illness was USD 51 per case. The OCV campaign economic cost was USD 289,561, 42% attributable to vaccine costs and 58% to service delivery costs. In our base case, the incremental cost was USD 1.9 million per death averted, USD 1745 per case averted, and USD 69,892 per DALY averted. Sensitivity analyses that increased the CFR to 0.35% or the IR to 10.4 cases per 1000 resulted in a cost per DALY of USD 15,666. The low multi-year average CFR and incidence of the cholera outbreaks in the Maela camp were key factors associated with the high cost per DALY averted. However, the sensitivity analyses indicated higher cost-effectiveness in a setting with a higher CFR or cholera incidence, indicating when to consider campaign use to reduce the outbreak risk.

Oral cholera vaccine coverage in Goma, Democratic Republic of the Congo, 2022, following 2019–2020 targeted preventative mass campaigns

BackgroundIn 2019–2020, preventative Oral Cholera Vaccine campaigns were conducted in 24/32 non-contiguous health areas of Goma, DR Congo. In August 2022, we measured coverage and factors potentially influencing success of the delivery strategy. MethodsWe used random geo-sampled stratified cluster survey to estimate OCV coverage and assess population movement, diarrhea history, and reasons for non-vaccination. Results603 households were visited. Coverage with at least one dose was 46.4 % (95 %CI: 41.8–51.0), and 50.1 % (95 %CI: 45.4–54.8) in areas targeted by vaccination compared to 26.3 % (95 %CI: 19.2–34.9) in non-targeted areas. Additionally, 7.0 % of participants reported moving from outside Goma since 2019, and 5.4 % reported history of severe diarrhea. Absence and unawareness were the main reasons for non-vaccination. ConclusionResults suggest that targeting non-contiguous urban areas had a coverage-diluting effect. Targeting entire geographically contiguous areas, adapted distribution, and regular catch-up campaigns are operational recommendations to reach higher coverages arising from the study.

Diarrhea and cholera surveillance for early warning and preparedness to prevent epidemics among Rohingya Myanmar nationals in Cox's Bazar, Bangladesh

Diarrheal diseases, especially cholera, can be a serious threat to Rohingya refugees in Cox's Bazar due to overcrowding and inadequate hygiene infrastructure. Assessing the risk, cholera surveillance network was established with the aim to identify the outbreak of diarrhea and cholera and help to take appropriate preventive measures including a vaccination campaign. The surveillance network has been ongoing for 6 years (2017–2023) in 17 health facilities. Diarrhea patients from Rohingya Myanmar nationals matched with case definition were enrolled and stool samples were tested by Rapid diagnostic test (RDT) for early cholera detection Multiple Logistic regression models were fitted to examine the associations of risk factors among cholera cases. A total of 17,252 stool samples were collected through surveillance. Among the tested samples, 588 (3.5 %) were detected positive by RDT, and 239 (1.4 %) Vibrio cholerae were isolated by microbiological culture. Between 2021 and 2023, the number of culture-confirmed cases exceeded that in the period from 2017 to 2020. In addition to V. cholerae; high positivity was identified for ETEC (11.8 %) followed by Salmonella (3.9 %) and Shigella (2.7 %). Most of the cholera cases were presented with vomiting, dehydration and loose watery and rice watery nature of stool (p value = <0.001). Major risk factors for cholera were 2–4 years age group (OR = 5.72; 95 % CI, 3.84–8.53.14; P = .001), process of water treatment (OR = 1.54; 95 % CI, 1.01–2.37; P = .046) and hand washing with soap before taking meals (OR = 0.6; 95 % CI, 0.39–0.92; P = .020. This study highlights the epidemiology of cholera among the Rohingya population and underscores the effectiveness of integrating surveillance data with early warning, alert, and response systems (EWARS) system, along with oral cholera vaccine (OCV) campaigns, in preventing major cholera outbreak.

Comprehensive Review on the Use of Oral Cholera Vaccine (OCV) in Ethiopia: 2019 to 2023.

Cholera outbreaks in Ethiopia necessitate frequent mass oral cholera vaccine (OCV) campaigns. Despite this, there is a notable absence of a comprehensive summary of these campaigns. Understanding national OCV vaccination history is essential to design appropriate and effective cholera control strategies. Here, we aimed to retrospectively review all OCV vaccination campaigns conducted across Ethiopia between 2019 and 2023. The OCV request records from 2019 to October 2023 and vaccination campaign reports for the period from 2019 to December 2023 were retrospectively accessed from the Ethiopia Public Health Institute (EPHI) database. Descriptive analysis was conducted using the retrospective data collected. From 2019 to October 2023, Ethiopian government requested 32 044 576 OCV doses (31 899 576 doses to global stockpile; 145 000 doses to outside of stockpile). Around 66.3% of requested doses were approved; of which 90.4% were received. Fifteen OCV campaigns (12 reactive and 3 pre-emptive) were conducted, including five two-dose campaigns with varying dose intervals and single-dose campaigns partially in 2019 and entirely in 2021, 2022 and 2023. Overall vaccine administrative coverage was high; except for Tigray region (41.8% in the 1st round; 2nd round didn't occur). The vaccine administrative coverage records were documented, but no OCV coverage survey data was available. This study represents the first comprehensive review of OCV campaigns in Ethiopia spanning the last five years. Its findings offer valuable insights into informing future cholera control strategies, underscoring the importance of monitoring and evaluation despite resource constraints. Addressing the limitations in coverage survey data availability is crucial for enhancing the efficacy of future campaigns.

Coverage of Two-Dose Preemptive Cholera Mass Vaccination Campaign in High-Priority Hotspots in Shashemene, Oromia Region, Ethiopia.

Cholera is a public health priority in Ethiopia. The Ethiopian National Cholera Plan elaborates a multi-year scheme of oral cholera vaccine (OCV) use. Aligned with this, a preemptive OCV campaign was conducted under our Ethiopia Cholera Control and Prevention project. Here, we present the OCV vaccination outcomes. Cholera high-priority hotspots in the Oromia Region, Shashemene Town (ST) and Shashemene Woreda (SW), were selected. Four kebelles (Abosto, Alelu, Arada, and Awasho) in ST and 4 clusters (Faji Gole, Harabate, Toga, and Chabi) in SW were study sites with OCV areas nested within. A total of 40 000 and 60 000 people in ST and SW, respectively, were targeted for a 2-dose OCV (Euvichol-Plus) campaign in 11-15 May (first round [R1]) and 27-31 May (second round [R2]) 2022. Daily administrative OCV coverage and a coverage survey in 277 randomly selected households were conducted. The administrative OCV coverage was high: 102.0% for R1 and 100.5% for R2 in ST and 99.1% (R1) and 100.0% (R1) in SW. The coverage survey showed 78.0% (95% confidence interval [CI]: 73.1-82.9) of household members with 2-dose OCV and 16.8% (95% CI: 12.4-21.3) with no OCV in ST; and 83.1% (95% CI: 79.6-86.5) with 2-dose OCV and 11.8% (95% CI: 8.8-14.8) with no OCV in SW. The 2-dose coverages in 1-4-, 5-14-, and ≥15-year age groups were 88.3% (95% CI: 70.6-96.1), 88.9% (95% CI: 82.1-95.7), and 71.3% (95% CI: 64.2-78.3), respectively, in ST and 78.2% (95% CI: 68.8-87.7), 91.0% (95% CI: 86.6-95.3), and 78.7% (95% CI: 73.2-84.1) in SW. High 2-dose OCV coverage was achieved. Cholera surveillance is needed to assess the vaccine impact and effectiveness.

Effectiveness of the Euvichol® oral cholera vaccine at 2 years: A case-control and bias-indicator study in Haiti

ObjectivesThe World Health Organization recommends the use of oral cholera vaccine (OCV) in cholera control efforts. Euvichol®, pre-qualified in 2015, is the leading component of the Global OCV stockpile, but data on its field effectiveness are limited. To evaluate Euvichol® vaccine effectiveness (VE), we conducted a case-control study between September 2018 to March 2020 following an OCV campaign in November 2017 in Haiti. MethodsCases were individuals with acute watery diarrhea. Stool samples were tested by culture and real-time polymerase chain reaction of the Vibrio cholerae ctxA gene. Cases were matched to four community controls without diarrhea by residence, enrollment time, age, and gender, and interviewed for sociodemographics, risk factors, and self-reported vaccination. Cholera cases were analyzed by conditional logistic regression in the VE study. Non-cholera diarrhea cases were analyzed in a bias-indicator study. ResultsWe enrolled 15 cholera cases matched to 60 controls, and 63 non-cholera diarrhea cases matched to 249 controls. In the VE analysis, eight (53%) cases reported vaccination with any number of doses compared to 43 (72%) controls. Adjusted two-dose OCV VE was 69% (95% CI –71 to 94%). ConclusionsBetween 10-27 months after vaccination, Euvichol® was effective and similar to Shanchol™, suggesting that it can serve as one component of multi-sectoral comprehensive cholera control.

Euvichol-plus vaccine campaign coverage during the 2017/2018 cholera outbreak in Lusaka district, Zambia: a cross-sectional descriptive study

ObjectiveTo determine the coverage for the oral cholera vaccine (OCV) campaign conducted during the 2017/2018 cholera outbreak in Lusaka, Zambia.Study designA descriptive cross-sectional study employing survey method conducted among 1691...

Implementation and Delivery of Oral Cholera Vaccination Campaigns in Humanitarian Crisis Settings among Rohingya Myanmar nationals in Cox's Bazar, Bangladesh.

Over 700,000 Myanmar nationals known as the 'Rohingyas' fled into Cox's Bazar, Bangladesh, in late 2017. Due to this huge displacement into unhygienic areas, these people became vulnerable to communicable diseases including cholera. Assessing the risk, the Government of Bangladesh (GoB), with the help of the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) and other international partners, decided to take preventive measures, one of which is the execution of oral cholera vaccination (OCV) campaigns. This paper describes the implementation and delivery of OCV campaigns during humanitarian crises in Bangladesh. Seven rounds of OCV campaigns were conducted between October 2017 and December 2021. The OCV campaigns were conducted by applying different strategies. Approximately 900,000 Rohingya Myanmar nationals (RMNs) and the host population (amounting to 528,297) received OCV across seven campaigns. In total, 4,661,187 doses of OCVs were administered, which included 765,499 doses for RMNs, and 895,688 doses for the host community. The vaccine was well accepted, and as a result, a high level of coverage was achieved, ranging from 87% to 108% in different campaigns. After successful pre-emptive campaigns in Cox's Bazar humanitarian camps, no cholera outbreaks were detected either in the RMN or host communities.

Recent surge in cholera outbreaks globally during the COVID-19 pandemic era: a potential threat to the African continent and salient counteracting strategies.

Recent surge in cholera outbreaks globally during the COVID-19 pandemic era: a potential threat to the African continent and salient counteracting strategies.

Coverage survey and lessons learned from a pre-emptive cholera vaccination campaign in urban and rural communities affected by landslides and floods in Freetown Sierra Leone.

On 14 August 2017, massive landslides and floods hit Freetown (Sierra Leone). More than 1,000 people lost their lives while approximately 6,000 people were displaced. The areas most affected included parts of the town with challenged access to basic water and sanitation facilities, with communal water sources likely contaminated by the disaster. To avert a possible cholera outbreak following this emergency, the Ministry of Health and Sanitation (MoHS), supported by the World Health Organization (WHO) and international partners, including Médecins Sans Frontières (MSF) and UNICEF, launched a two-dose pre-emptive vaccination campaign using Euvichol™, an oral cholera vaccine (OCV). We conducted a stratified cluster survey to estimate vaccination coverage during the OCV campaign and also monitor adverse events. The study population - subsequently stratified by age group and residence area type (urban/rural) - included all individuals aged 1year or older, living in one of the 25 communities targeted for vaccination. In total 3,115 households were visited, 7,189 individuals interviewed; 2,822 (39%) people in rural and 4,367 (61%) in urban areas. The two-dose vaccination coverage was 56% (95% confidence interval (CI): 51.0-61.5), 44% (95%CI: 35.2-53.0) in rural and 57% (95%CI: 51.6-62.8) in urban areas. Vaccination coverage with at least one dose was 82% (95%CI: 77.3-85.5), 61% (95%CI: 52.0-70.2) in rural and 83% (95%CI: 78.5-87.1) in urban areas. The Freetown OCV campaign exemplified a timely public health intervention to prevent a cholera outbreak, even if coverage was lower than expected. We hypothesised that vaccination coverage in Freetown was sufficient in providing at least short-term immunity to the population. However, long-term interventions to ensure access to safe water and sanitation are needed.

Cholera Outbreak - Haiti, September 2022-January 2023.

On September 30, 2022, after >3 years with no confirmed cholera cases (1), the Directorate of Epidemiology, Laboratories and Research (DELR) of the Haitian Ministry of Public Health and Population (Ministère de la Santé Publique et de la Population [MSPP]) was notified of two patients with acute, watery diarrhea in the metropolitan area of Port-au-Prince. Within 2 days, Haiti's National Public Health Laboratory confirmed the bacterium Vibrio cholerae O1 in specimens from the two patients with suspected cholera infection, and an outbreak investigation began immediately. As of January 3, 2023, >20,000 suspected cholera cases had been reported throughout the country, and 79% of patients have been hospitalized. The moving 14-day case fatality ratio (CFR) was 3.0%. Cholera, which is transmitted through ingestion of water or food contaminated with fecal matter, can cause acute, severe, watery diarrhea that can rapidly lead to dehydration, shock, and death if not treated promptly (2). Haiti is currently facing ongoing worsening of gang violence, population displacement, social unrest, and insecurity, particularly in the metropolitan area of Port-au-Prince, including Belair, Bas-Delmas, Centre-Ville, Martissant, Cité Soleil, Croix-des Bouquets, and Tabarre, creating an environment that has facilitated the current resurgence of cholera (3). This report describes the initial investigation, ongoing outbreak, and public health response to cholera in Haiti. Cholera outbreak responses require a multipronged, multisectoral approach including surveillance; case management; access to safe water, sanitation, and hygiene (WASH) services; targeted oral cholera vaccine (OCV) campaigns; risk communication; and community engagement. This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy.

Cost of oral cholera vaccine delivery in a mass immunization program for children in urban Bangladesh

Cholera poses a substantial health burden in the developing world due to both epidemic and endemic diseases. The World Health Organization recommends oral cholera vaccines for mass vaccination campaigns in addition to traditional prevention practices and treatments in resource-poor settings. In many developing countries like Bangladesh, the major challenge behind implementing mass vaccination campaigns concerns the affordability of the oral cholera vaccine (OCV). Vaccination of children with OCV is not only an impactful approach for controlling cholera at the population level and reducing childhood morbidity but is also considered more cost-effective than vaccinating all ages. The aim of the study was to estimate the cost of an OCV campaign for children from a societal perspective using empirical study. A total of 66,311 children aged 1 to 14 years old were fully vaccinated with two doses of the OCV Shanchol while 9,035 individuals received one dose of this vaccine. The estimated societal cost per individual for full vaccination was US$ 6.11, which includes the cost of vaccine delivery estimated at US$ 1.95. The cost per single dose was estimated at US$ 2.86. The total provider cost for full vaccination was estimated at US$ 6.01 and the recipient cost at US$ 0.10. Our estimation of OCV delivery costs for children was relatively higher than what was found in a similar mass OCV campaign for all age groups, indicating that there may be additional cost factors to consider in targeted vaccine campaigns. This analysis provides useful benchmarks for the possible costs related to delivery of OCV to children and future OCV cost-effectiveness models should factor in these possible cost disparities. Attempts to reduce the cost per dose are likely to have a greater impact on the cost of similar vaccination campaigns in many resource-poor settings.

Pre-emptive oral cholera vaccine (OCV) mass vaccination campaign in Cuamba District, Niassa Province, Mozambique: feasibility, vaccination coverage and delivery costs using CholTool

IntroductionMozambique suffers from regular floods along its principal river basins and periodic cyclones that resulted in several cholera epidemics during the last decades. Cholera outbreaks in the recent 5 years...

An innovative approach in monitoring oral cholera vaccination campaign: integration of a between-round survey

BackgroundMonitoring and Evaluation (M&E) is essential in ensuring population’s access to immunization. Surveys are part of this M&E approach but its timing limits the use of its results to improve the coverage of the evaluated campaign. An oral cholera vaccination campaign was organized in a health district of the Far North region of Cameroon and involved an innovative M&E approach. The aim of this project was to assess the feasibility and effect of using recommendations of a community-based immunization and communication coverage survey conducted after the first round of an OCV campaign on the coverage of the second-round of the campaign.MethodsTwo community-based surveys were included in the M&E plan and conducted at the end of each of the campaign rounds. Data were collected by trained and closely supervised surveyors and reported using smartphones. Key results of the first-round survey were disseminated to campaign implementing team prior to the second round. The two rounds of the pre-emptive campaign were organized by the Cameroon Ministry of Public Health and partners with a two-week interval in the Mogode Health District of the Far North region of Cameroon in May and June 2017.ResultsOf 120 targeted clusters, 119 (99.1%) and 117 (97.5%) were reached for the first and second rounds respectively. Among the Mogode population eligible for vaccination, the immunization coverage based on evidence (card or finger mark) were estimated at 81.0% in the first round and increased to 88.8% in the second round (X2=69.0 and p <0.00). For the second round, we estimated 80.1% and 4.3% of persons who were administered 2 doses and 1 dose of OCV with evidence respectively, and 3.8% of persons who have not been vaccinated. The distribution of campaign communication coverage per health area was shared with the campaign coordination team for better planning of the second round campaign activities.ConclusionsIt is feasible to plan and implement coverage survey after first round OCV campaign and use its results for the better planning of the second round. For the present study, this is associated to the improvement of OCV coverage in the second-round vaccination. If this is persistent in other contexts, it may apply to improve coverage of any health campaign that is organized in more than one round.

Cholera outbreak in Forcibly Displaced Myanmar National (FDMN) from a small population segment in Cox's Bazar, Bangladesh, 2019.

Bangladesh experienced a sudden, large influx of forcibly displaced persons from Myanmar in August 2017. A cholera outbreak occurred in the displaced population during September-December 2019. This study aims to describe the epidemiologic characteristics of cholera patients who were hospitalized in diarrhea treatment centers (DTCs) and sought care from settlements of Forcibly Displaced Myanmar Nationals (FDMN) as well as host country nationals during the cholera outbreak. Diarrhea Treatment Center (DTC) based surveillance was carried out among the FDMN and host population in Teknaf and Leda DTCs hospitalized for cholera during September-December 2019. During the study period, 147 individuals with cholera were hospitalized. The majority, 72% of patients reported to Leda DTC. Nearly 65% sought care from FDMN settlements. About 47% of the cholera individuals were children less than 5 years old and 42% were aged 15 years and more. Half of the cholera patients were females. FDMN often reported from Camp # 26 (45%), followed by Camp # 24 (36%), and Camp # 27 (12%). Eighty-two percent of the cholera patients reported watery diarrhea. Some or severe dehydration was observed in 65% of cholera individuals. Eighty-one percent of people with cholera received pre-packaged ORS at home. About 88% of FDMN cholera patients reported consumption of public tap water. Pit latrine without water seal was often used by FDMN cholera individuals (78%). Vigilance for cholera patients by routine surveillance, preparedness, and response readiness for surges and oral cholera vaccination campaigns can alleviate the threats of cholera.

A reactive vaccination campaign with single dose oral cholera vaccine (OCV) during a cholera outbreak in Cameroon

BackgroundCameroon chose Oral Cholera Vaccine (OCV) mass vaccination campaign in addition to other interventions to respond to outbreaks since 2015. There is still a persistent controversy on the effectiveness of reactive OCV mass vaccination campaign. ObjectiveThis article aimed to share evidence-based observations on the effect of a reactive single-dose OCV mass vaccination campaign on cholera cases in Cameroon. MethodsHealth area centered risk analysis was used to identify nine high risk health areas among four health districts in the |North Region as hotspots. About 537,274 people at risk of cholera transmission one year of age and above including pregnant women were eligible to receive OCV. A total of 537,279 doses of OCV was deployed for vaccination from August 1–5, 2019 through door-to-door strategy for urban health districts, and fixed/ temporary fixed posts strategies for rural health districts. ResultsThe overall vaccination coverage was 99.9%. Vaccine wastage rate was less than 0.5% (0.0011%). Independent monitoring showed vaccination coverage at 97.2%. The 2019 epidemic curve went down after OCV intervention on the contrary to that in the year 2018 at the same period. After OCV intervention, cholera cases dropped from about 10.5 to 9.3 cases per week at the regional level while at the district level, they dropped from 5.3 to 2.1, 2.2 to 1.7, 0.6 to 0 and 1.7 to 1.5 cases per week respectively for Garoua, Garoua II, Tchollire and Pitoa. Though not statistically significant (p = 1.4, α = 0.05), cases per 1000 population seemed to remain unchanged among OCV zones (0.32/1000) and non-OCV zones (0.31/1000) in 2018 while they increased from 0.37 (OCV zones) to 0.53 (non-0CV zones) cases per 1000 population in 2019. ConclusionThere might have been a general trend in the reduction of the number of new cases after a reactive single-dose OCV campaign.

Use of surveys to evaluate an integrated oral cholera vaccine campaign in response to a cholera outbreak in Hoima district, Uganda

ObjectivesTo evaluate the quality and coverage of the campaign to distribute oral cholera vaccine (OCV) during a cholera outbreak in Hoima, Uganda to guide future campaigns of cholera vaccine.DesignSurvey of...

Achieving coordinated national immunity and cholera elimination in Haiti through vaccination: a modelling study

SummaryBackgroundCholera was introduced into Haiti in 2010. Since then, more than 820 000 cases and nearly 10 000 deaths have been reported. Oral cholera vaccine (OCV) is safe and effective, but has not been seen as a primary tool for cholera elimination due to a limited period of protection and constrained supplies. Regionally, epidemic cholera is contained to the island of Hispaniola, and the lowest numbers of cases since the epidemic began were reported in 2019. Hence, Haiti may represent a unique opportunity to eliminate cholera with OCV.MethodsIn this modelling study, we assessed the probability of elimination, time to elimination, and percentage of cases averted with OCV campaign scenarios in Haiti through simulations from four modelling teams. For a 10-year period from January 19, 2019, to Jan 13, 2029, we compared a no vaccination scenario with five OCV campaign scenarios that differed in geographical scope, coverage, and rollout duration. Teams used weekly department-level reports of suspected cholera cases from the Haiti Ministry of Public Health and Population to calibrate the models and used common vaccine-related assumptions, but other model features were determined independently.FindingsAmong campaigns with the same vaccination coverage (70% fully vaccinated), the median probability of elimination after 5 years was 0–18% for no vaccination, 0–33% for 2-year campaigns focused in the two departments with the highest historical incidence, 0–72% for three-department campaigns, and 35–100% for nationwide campaigns. Two-department campaigns averted a median of 12–58% of infections, three-department campaigns averted 29–80% of infections, and national campaigns averted 58–95% of infections. Extending the national campaign to a 5-year rollout (compared to a 2-year rollout), reduced the probability of elimination to 0–95% and the proportion of cases averted to 37–86%.InterpretationModels suggest that the probability of achieving zero transmission of Vibrio cholerae in Haiti with current methods of control is low, and that bolder action is needed to promote elimination of cholera from the region. Large-scale cholera vaccination campaigns in Haiti would offer the opportunity to synchronise nationwide immunity, providing near-term population protection while improvements to water and sanitation promote long-term cholera elimination.FundingBill & Melinda Gates Foundation, Global Good Fund, Institute for Disease Modeling, Swiss National Science Foundation, and US National Institutes of Health.

The Effect of Oral Cholera Vaccine in Response to an Outbreak of Cholera in aComplex Emergency, Borno State, Northeast Nigeria.

Background: Cholera Outbreak remains a global health threat amongst Internally Displaced Persons (IDPs) and areas facing complex emergencies. The insurgency in Northeast Nigeria disrupted social services and displaced thousands into IDPs camps which are overcrowded with sub-optimal water, sanitation, and hygiene. We confirmed, characterized the outbreak and instituted control measures which include the first-ever use of Oral Cholera Vaccine (OCV) in Nigeria. Methods: We defined a suspected cholera case-patient as any person above two (≥ 2) years of age presenting with Acute Watery Diarrhea (AWD) and severe dehydration or dying from AWD, with or without vomiting between 14th August to 21st December 2017. We conducted a descriptive and analytic study. Using the Polio vaccination structure, we launched an OCV campaign in two phases (rounds) targeting all people above one (≥ 1) year of age in the affected communities and IDP camps. Results: We identified 6,430 case-patients with 61 deaths in seven (7) Local Government Areas (LGAs) of Borno State which include 3,512 (54.62%) in Jere, 1,870 (29.08%) Monguno, 845 (13.14%) Dikwa, 115 (1.79%) Guzamala, 63 (0.98%) Maiduguri, 23 (0.36%) Mafa and 2 (0.03%) in Gubio. Most of the case-patients 6,109 (95%) were IDPs living in camps. The median age was nine (9) years (Range: 2-80). Females 2,780 (43%) were most affected than males. We targeted a total of 855,492 individuals above one year of age in the affected LGAs for an OCV. We vaccinated 896,919 individuals using 914,565 doses of OCV, giving a coverage rate of 105%. The wastage rate was 0.4%. We did not report any Adverse Events Following Immunization (AEFI). On OCV day four, 122 was the highest number of daily reported case-patients after which the daily case count began to decline until the end of the outbreak. The overall case fatality rate (CFR:0.95%) was 0.95%. Conclusion: The protracted cholera outbreak increased in magnitude and strength, and affected mostly children living in IDPs camps. The cholera outbreak was rapidly detected, and the response was timely, which might have been a possible reason for the low CFR. The reactive OCV might have influenced the ending of the outbreak. Despite the complex and challenging context, we were able to contain the outbreak within four months with a low CFR.