Safety, immunogenicity, and lot stability of the whole cell/recombinant B subunit (WC/rCTB) cholera vaccine in Peruvian adults and children

Effect of HIV status and retinol on immunogenicity to oral cholera vaccine in adult population living in an endemic area of Lukanga Swamps, Zambia

Background

We set out to assess the impact of human immunodeficiency virus (HIV) and micronutrient deficiency as indicated by serum retinol levels on the immune responses to Oral Cholera Vaccine (Shanchol™) in a cohort of participants in Lukanga Swamps, Zambia. Cholera remains endemic in Zambia with vaccines being the only effective preventive measures. However, the effect of these vaccines on populations living with HIV has not been widely documented.

Methods

HIV testing and confirmation was done using the Alere Determine™ HIV-1/2 and Uni-Gold™ kits while vibriocidal antibody assay was applied for vaccine immunogenicity. Serum retinol analysis was assessed by Shimadzu Prominence HCT-2010 High Performance Liquid Chromatography (HPLC). The primary outcome was log transformed geometric mean titre.

Results

From 47 participants screened for HIV, 51% (24) tested positive. There was a statistically significant reduction in Ogawa geometric mean ratio (GMR) by 67% (GMR = 0.33; 95% CI: -0.15, 0.76; p-value = 0.009) attributable to HIV positivity with a non-significant reduction in Inaba GMR by about 50% due to HIV positivity. When doubling of retinol levels modelled, GMR reduction against Ogawa were non-significant but that against Inaba resulted in a significant reduction in geometric mean titer (GMT) (GMT-0.33, C.I 0.16–0.66, p-value 0.002). At 1000copies/ml viral load cut off and 350 cells/μl CD4 counts, Ogawa GMT was two times higher 11.16 (95%CI: 8.20–15.19) versus 6.06 (95%CI: 4.04–9.10) in low viremia participants, and three times higher in above threshold CD4 count participants; 24.81 (95%CI: 18.94–32.50) versus 7.07 (95%CI: 5.22–9.58).

Conclusion

Our results show that while Shanchol™ is immunogenic in both HIV+/- individuals, HIV + participants responded poorly. Viral load and CD4 count affected vaccine immunogenicity. More research is required for detailed understanding of this in order to appropriately inform policy and practice.

Augmented immune responses to a booster dose of oral cholera vaccine in Bangladeshi children less than 5 years of age: Revaccination after an interval of over three years of primary vaccination with a single dose of vaccine

We have earlier reported that a single dose of oral cholera vaccine (OCV) is protective in adults and children ≥5 years of age and sustained for 2 years. We enrolled participants (n = 240) from this study, between March-September 2017, over 3 years after receiving a primary single dose. Immune responses were measured in placebo group (Primary Immunization group: PI) and compared with those who received a single dose (Booster Immunization group: BI). The children were 4 to <5 years, 5 to <18 years and adults >18 years. Blood was collected at day 0 (before vaccination) and after receiving 1st and 2nd doses of OCV. Overall, the BI and PI groups showed vibriocidal antibody response after 1st and 2nd dose of vaccination in all age groups to V. cholerae O1 and O139. Young children in the BI group showed significantly higher vibriocidal antibody response two weeks after receiving the first dose as compared to PI group to LPS. Elevated plasma IgA responses to LPS after the first dose were observed among the BI group compared to the PI group among the young children. Mucosal antibody responses measured in fecal extracts showed similar increases as that of vibriocidal and LPS responses in the BI group. These results suggest a single boosting dose of OCV generated immune response in primed population >5 years of age who had earlier received OCV. However, young children who had received OCV earlier, boosting after a single dose, resulted in increased immune responses compared to the PI group. Further studies are needed to assess protection obtained from different strategies, especially for young children and to determine the numbers of primary and booster doses needed. In addition, more information is needed regarding the optimum interval between primary and booster doses to plan future interventions for cholera control. ClinicalTrials.gov Identifier: NCT02027207.

Vedolizumab affects antibody responses to immunisation selectively in the gastrointestinal tract: randomised controlled trial results

OBJECTIVE

The α4β7 integrin monoclonal antibody vedolizumab is hypothesised to be gut selective. Effects of vedolizumab on immune responses to parenterally or enterally administered antigens were investigated.

DESIGN

In this randomised, double-blind, placebo-controlled, phase I trial, healthy participants received a single intravenous dose of vedolizumab 750 mg (n=64) or placebo (n=63). After 4 days, participants began intramuscular hepatitis B vaccine (HBV; days 4, 32, 60) and oral cholera vaccine (OCV; days 4, 18) regimens. The study was designed to demonstrate a 15% non-inferiority margin for the between-group difference in the primary end point: percentage of participants with HBV seroconversion at day 74 (serum hepatitis B surface antigen (HBs) antibody titre ≥10 IU/L). OCV seroconversion at day 74 (>4-fold increase in serum cholera toxin (CT) antibodies) was a secondary end point.

RESULTS

A total of 56 (90.3%) placebo-treated and 54 (88.5%) vedolizumab-treated participants responded to HBV. Geometric mean anti-HBs titres were similar for placebo (114.4 IU/L) and vedolizumab (129.6 IU/L) at day 74. A total of 60 (96.8%) placebo-treated and 52 (82.5%) vedolizumab-treated participants responded to OCV at day 74. Geometric mean anti-CT IgG levels were higher for placebo than for vedolizumab at day 74 (9210.08 vs. 3007.8 ELISA Units (EU)/mL) and day 32 (11629.3 vs. 1575.4 EU/mL). Anti-CT IgA results were similar. Adverse events were consistent with previous experience. One serious adverse event (spontaneous abortion) was reported for placebo.

CONCLUSIONS

Vedolizumab did not alter the response to parenterally administered antigens but reduced the response to oral antigens, demonstrating its gut-selective mechanism of action.

TRIAL REGISTRATION NUMBER

NCT Number: 01981616; EudraCT Number: 2011-001874-24.

Safety and immunogenicity assessment of an oral cholera vaccine through phase I clinical trial in Korea

The safety, tolerability and immunogenicity of an oral cholera vaccine (OCV) was assessed in adult Korean male through an open-label, non-comparative clinical study. Two doses of vaccine with an interval of 2 weeks were given to 20 healthy subjects. A total of 7 adverse events occurred in 6 subjects. However, no clinically significant change was observed in electrocardiograms, vital signs, physical examinations, and clinical laboratory tests. The immunogenicity of OCV was evaluated by serum vibriocidal assay where anti-Vibrio cholerae O1 and O139 antibodies were measured at day 0, 14, and 28 of vaccine administration. The antibody titers ranged from < 2.5-5,120 for V. cholerae O1 Inaba, < 2.5-10,240 for V. cholerae O1 Ogawa and < 2.5-480 for V. cholerae O139. In addition, the fold increase in antibody titers ranged from 1-4,096 for O1 Inaba, 1-8,192 for O1 Ogawa, and 1-384 for O139. The seroconversion rate was 95% and 45% for O1 and O139 antibodies, respectively. Our study clearly shows that administration of two doses of OCV at a 2 week-interval increases an appropriate level of antibody titer in the serum of healthy Korean adult males (Clinical Trial Number, NCT01707537).

The ABCs (Antibody, B Cells, and Carbohydrate Epitopes) of Cholera Immunity: Considerations for an Improved Vaccine

Cholera, a diarrheal disease, is known for explosive epidemics that can quickly kill thousands. Endemic cholera is a seasonal torment that also has a significant mortality. Not all nations with extensive rural communities can achieve the required infrastructure or behavioral changes to prevent epidemic or endemic cholera. For some communities, a single-dose cholera vaccine that protects those at risk is the most efficacious means to reduce morbidity and mortality. It is clear that our understanding of what a protective cholera immune response is has not progressed at the rate our understanding of the pathogenesis and molecular biology of cholera infection has. This review addresses V. cholerae lipopolysaccharide (LPS)-based immunogens because LPS is the only immunogen proven to induce protective antibody in humans. We discuss the role of anti-LPS antibodies in protection from cholera, the importance and the potential role of B cell subsets in protection that is based on their anatomical location and the intrinsic antigen-receptor specificity of various subsets is introduced.

Vaccines for the prevention of diarrhea due to cholera, shigella, ETEC and rotavirus

Background

Diarrhea is a leading cause of mortality in children under 5 years along with its long-term impact on growth and cognitive development. Despite advances in the understanding of diarrheal disorders and management strategies, globally nearly 750,000 children die annually as a consequence of diarrhea.

Methods

We conducted a systematic review of the efficacy and effectiveness studies. We used a standardized abstraction and grading format and performed meta-analyses for all outcomes. The estimated effect of cholera, shigella, Enterotoxigenic Escherichia coli (ETEC) and rotavirus vaccines was determined by applying the standard Child Health Epidemiology Reference Group (CHERG) rules.

Results

A total of 24 papers were selected and analyzed for all the four vaccines. Based on the evidence, we propose a 74% mortality reduction in rotavirus specific mortality, 52% reduction in cholera incidence due to their respective vaccines. We did not find sufficient evidence and a suitable outcome to project mortality reductions for cholera, ETEC and shigella in children under 5 years.

Conclusion

Vaccines for rotavirus and cholera have the potential to reduce diarrhea morbidity and mortality burden. But there is no substantial evidence of efficacy for ETEC and shigella vaccines, although several promising vaccine concepts are moving from the development and testing pipeline towards efficacy and Phase 3 trials.

Immune responses to cholera in children

Cholera is a severe acute dehydrating diarrheal disease caused by Vibrio cholerae O1 or O139 infection, and is associated with significant mortality and morbidity globally. Although young children bear a high burden of the disease, currently available oral vaccines give a lower efficacy and shorter duration of protection in this group than in adults. According to the studies of natural infection, young children achieve comparable systemic anti-V. cholerae antigen-specific antibody, gut-homing antibody-secreting cell and memory B-cell responses as adults. Studies on innate and cell-mediated immune responses are lacking in children, and may offer important insights into differences in vaccine efficacy. The impact of host factors such as malnutrition, genetics and coinfection with other pathogens also remains to be fully defined.

Memory B cell and other immune responses in children receiving two doses of an oral killed cholera vaccine compared to responses following natural cholera infection in Bangladesh

Current oral cholera vaccines induce lower protective efficacy and shorter duration of protection against cholera than wild-type infection provides, and this difference is most pronounced in young children. Despite this, there are limited data comparing immune responses in children following wild-type disease versus vaccination, especially with regard to memory responses associated with long-term immunity. Here, we report a comparison of immune responses in young children (2 to 5 years of age; n = 20) and older children (6 to 17 years of age; n = 20) given two doses of an oral killed cholera vaccine containing recombinant cholera toxin B subunit (CtxB) 14 days apart and compare these responses to those induced in similarly aged children recovering from infection with Vibrio cholerae O1 Ogawa in Bangladesh. We found that the two vaccine groups had comparable vibriocidal and lipopolysaccharide (LPS)-specific plasma antibody responses. Vaccinees developed lower levels of IgG memory B cell (MBC) responses against CtxB but no significant MBC responses against LPS. In contrast, children recovering from natural cholera infection developed prominent LPS IgG and IgA MBC responses, as well as CtxB IgG MBC responses. Plasma LPS IgG, IgA, and IgM responses, as well as vibriocidal responses, were also significantly higher in children following disease than after vaccination. Our findings suggest that acute and memory immune responses following oral cholera vaccination in children are significantly lower than those observed following wild-type disease, especially responses targeting LPS. These findings may explain, in part, the lower efficacy of oral cholera vaccination in children.

Oral vaccines for preventing cholera

EDITORIAL NOTE

This review is superseded by the published Cochrane Review, Saif‐Ur‐Rahman 2024 [https://doi.org/10.1002/14651858.CD014573], which considers only the oral killed vaccines because the live oral vaccines do not have World Health Organization (WHO) prequalification. Saif‐Ur‐Rahman 2024 also considered only currently available WHO pre‐qualified oral killed cholera vaccines (Dukoral, Shanchol, and Euvichol/Euvichol‐Plus).

BACKGROUND

Cholera is a cause of acute watery diarrhoea which can cause dehydration and death if not adequately treated. It usually occurs in epidemics, and is associated with poverty and poor sanitation. Effective, cheap, and easy to administer vaccines could help prevent epidemics.

OBJECTIVES

To assess the effectiveness and safety of oral cholera vaccines in preventing cases of cholera and deaths from cholera.

SEARCH STRATEGY

In October 2010, we searched the Cochrane Infectious Disease Group Specialized Register; Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE; EMBASE; LILACS; the metaRegister of Controlled Trials (mRCT), and the WHO International Clinical Trials Registry Platform (ICTRP) for relevant published and ongoing trials.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials of oral cholera vaccines in healthy adults and children.

DATA COLLECTION AND ANALYSIS

Each trial was assessed for eligibility and risk of bias by two authors working independently. Data was extracted by two independent reviewers and analysed using the Review Manager 5 software. Outcomes are reported as vaccine protective efficacy (VE) with 95% confidence intervals (CIs).

MAIN RESULTS

Seven large efficacy trials, four small artificial challenge studies, and twenty-nine safety trials contributed data to this review.Five variations of a killed whole cell vaccine have been evaluated in large scale efficacy trials (four trials, 249935 participants). The overall vaccine efficacy during the first year was 52% (95% CI 35% to 65%), and during the second year was 62% (95% CI 51% to 62%). Protective efficacy was lower in children aged less than 5 years; 38% (95% CI 20% to 53%) compared to older children and adults; 66% (95% CI 57% to 73%).One trial of a killed whole cell vaccine amongst military recruits demonstrated 86% protective efficacy (95% CI 37% to 97%) in a small epidemic occurring within 4 weeks of the 2-dose schedule (one trial, 1426 participants). Efficacy data is not available beyond two years for the currently available vaccine formulations, but based on data from older trials is unlikely to last beyond three years.The safety data available on killed whole cell vaccines have not demonstrated any clinically significant increase in adverse events compared to placebo.Only one live attenuated vaccine has reached Phase III clinical evaluation and was not effective (one trial, 67508 participants). Two new candidate live attenuated vaccines have demonstrated clinical effectiveness in small artificial challenge studies, but are still in development.

AUTHORS' CONCLUSIONS

The currently available oral killed whole cell vaccines can prevent 50 to 60% of cholera episodes during the first two years after the primary vaccination schedule. The impact and cost-effectiveness of adopting oral cholera vaccines into the routine vaccination schedule of endemic countries will depend on the prevalence of cholera, the frequency of epidemics, and access to basic services providing rapid rehydration therapy.

A comparison of clinical and immunologic features in children and older patients hospitalized with severe cholera in Bangladesh

BACKGROUND

: Infection with Vibrio cholerae induces protection from subsequent severe disease, suggesting that an effective vaccine could be an important preventive strategy. Available vaccines provide less protection against cholera than natural infection, particularly in children.

METHODS

: We examined a cohort of 121 children (2 years-12 years of age) and 276 older patients (>12 years of age) hospitalized with cholera in Dhaka, Bangladesh over a 4-year period, to compare clinical features in older patients and children and immune responses to key antigens.

RESULTS

: Older patients had more severe disease. Children with cholera were more commonly retinol deficient, while zinc deficiency was equally prevalent in both groups. Children developed higher vibriocidal and serum immune responses to the B subunit of cholera toxin (CTB). In contrast, older patients mounted higher immune responses to 2 other key V. cholerae antigens, the lipopolysaccharide (LPS) and toxin coregulated pilus antigens (TcpA). We compared immune responses following infection with those occurring after receipt of a live, oral vaccine in both children and older patients in Bangladesh, during a similar time period. The response rates for vibriocidal and LPS antibodies were higher after infection than after vaccination. Both vaccinated older patients and children responded poorly to CTB and TcpA.

CONCLUSIONS

: Although children developed vigorous vibriocidal and CTB-specific responses following infection, they had lessened responses to LPS and TcpA compared with older patients, as well as lessened responses to vaccination. More studies need to be carried out to determine factors, including micronutrient interventions that can improve responses in children to both natural infection and vaccination.

A randomized, placebo-controlled trial of the bivalent killed, whole-cell, oral cholera vaccine in adults and children in a cholera endemic area in Kolkata, India

OBJECTIVES

An effective vaccine against cholera has been used for public health purposes in Vietnam since the 1990s. This vaccine was reformulated to meet WHO requirements. We assessed the safety and immunogenicity of the reformulated bivalent (Vibrio cholerae 01 and 0139) killed whole cell oral vaccine in a cholera endemic area in Kolkata, India.

DESIGN

Double-blind, randomized, placebo controlled trial.

SETTING

The trial was conducted in the clinical trial ward of the Infectious Diseases Hospital in Kolkata, India.

PARTICIPANTS

The participants were 101 healthy adults (males and non-pregnant females) aged 18-40 years and 100 healthy children (males and non-pregnant females) aged 1-17 years.

INTERVENTIONS

Participants were randomized to receive either the bivalent killed whole cell oral cholera vaccine or placebo (killed oral Escherichia coli K12).

OUTCOME MEASURES

For safety: proportion of subjects with adverse events during the duration of study participation. For immunogenicity: Proportion of subjects who had a > or = 4-fold rise in serum vibriocidal antibody titers 14 days after the second dose of vaccine or placebo.

RESULTS

Adverse reactions were observed with similar frequency among vaccine and placebo recipients in both age groups. Among adults 4% of vaccine and 8% of placebo recipients and among children 4% of vaccine and 2% of placebo recipients had at least one adverse event within 28 days of the first dose of the vaccine. Following immunization, 53% of adult and 80% of children vaccinees showed a > or = 4 fold rise in serum V. cholerae O1 vibriocidal antibody titers. A less pronounced response to V. cholerae O139 vibriocidal antibody titers post-immunization was noted among vaccinees.

CONCLUSIONS

We found the vaccine to be safe and immunogenic in a cholera-endemic area in India.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00119197.

Safety and immunogenicity of a reformulated Vietnamese bivalent killed, whole-cell, oral cholera vaccine in adults

Vietnam currently produces an orally administered, bivalent (O1 and O139) killed whole-cell vaccine and is the only country in the world with endemic cholera to use an oral cholera vaccine in public health practice. In order to allow international use, the vaccine had to be reformulated to meet World Health Organization (WHO) requirements. We performed a randomized, placebo controlled, safety and immunogenicity studies of this reformulated vaccine among Vietnamese adults. One hundred and forty-four subjects received the two-dose regimen and 143 had two blood samples obtained for analysis. We found that this reformulated oral killed whole-cell cholera vaccine was safe, well tolerated and highly immunogenic.

Oral cholera vaccines: use in clinical practice

Cholera continues to occur globally, particularly in sub-Saharan Africa and Asia. Oral cholera vaccines have been developed and have now been used for several years, primarily in traveller populations. The licensure in the European Union of a killed whole cell cholera vaccine combined with the recombinant B subunit of cholera toxin (rCTB-WC) has stimulated interest in protection against cholera. Because of the similarity between cholera toxin and the heat-labile toxin of Escherichia coli, a cause of travellers' diarrhoea, it has been proposed that the rCTB-WC vaccine may be used against travellers' diarrhoea. An analysis of trials of this vaccine against cholera (serotype O1) shows that for 4-6 months it will protect 61-86% of people living in cholera-endemic regions; lower levels of protection continue for 3 years. Protection wanes rapidly in young children. Because the risk of cholera for most travellers is extremely low, vaccination should be considered only for those working in relief or refugee settings or for those who will be travelling in cholera-epidemic areas and who will be unable to obtain prompt medical care. The vaccine can be expected to prevent 7% or less of cases of travellers' diarrhoea and should not be used for this purpose.

Calibrated serological techniques demonstrate significant different serum response rates to an oral killed cholera vaccine between Swedish and Nicaraguan children

Serum responses to oral cholera vaccines were assessed in three paediatric vaccine trials, two in León, Nicaragua and one in Stockholm, Sweden. A calibrated anti-cholera toxin B subunit (CTB) IgA ELISA was used together with an assay for vibriocidal antibodies. Swedish children had lower pre-vaccination levels of antibody, but serum responses were more pronounced in Swedish children than in Nicaraguan children. Post-vaccination levels of anti-toxin antibody were generally above those found after natural infections with enterotoxigenic Escherichia coli, that cross-reacts serologically with Vibrio cholerae. Adverse events seen after vaccination were generally mild and of little clinical significance.

Recent developments in cholera

Cholera continues to be an important public health problem among many poorer communities in Africa, Asia and South America, despite the bacteriology and epidemiology of the disease having been described over a century ago. Molecular techniques have enabled current researchers to gain new insights into pathogenicity, into the relationships between environmental and clinical strains, and into new strategies for vaccine development. The description of non-culturable 'dormant' strains in the environment and the effect of environmental factors on toxin gene regulation provide valuable clues to the ecology of the disease. Disease management continues to be based on urgent and appropriate rehydration, and recent community studies emphasize the need for effective local health services to provide this if case fatality rates are to remain low. While antimicrobial agents may play a role in case management and prophylaxis, the increasing prevalence of antimicrobial resistance must be addressed. New vaccine candidates, based on a molecular understanding of pathogenicity, provide scope for improved strategies for disease prevention, though the appropriate public health context for their use has not been determined. This review summarizes activities in these fields of cholera research and considers the continuing global problem of the disease.

New developments in the understanding of cholera

Recent advances in prevention and treatment of cholera have occurred in the areas of vaccine testing, modifications of oral-rehydration solutions (ORS), and antimicrobial treatment. Oral vaccines consisting of killed whole bacterial cells (WC) with and without the B-subunit of cholera toxin (BS) were shown to be effective in large trials in Bangladesh, Peru, and Vietnam. However, the trials did not resolve whether two or three doses of vaccine are required and whether BS adds significantly to the immune protection of WC. Live, attenuated bacterial vaccines that are immunogenic and have been shown protective in human volunteer studies are candidates for future field trials. Rehydration of patients is a life- saving effort. The best ORS contains rice powder in place of glucose, and solutions with reduced osmolarity (245 mOsm/L, sodium 75 mEq/L) are as effective as standard ORS. Ciprofloxacin in a single dose is effective in adults, and erythromycin or ampicillin in multiple doses is effective in children.