Pregnancy outcomes after a mass vaccination campaign with an oral cholera vaccine: a systematic review and meta-analysis

Cholera Infection Risks and Cholera Vaccine Safety in Pregnancy

Introduction

Discuss the impact of cholera infection on pregnant women, fetus, and neonates and review the safety of cholera vaccines in pregnancy.

Methods

This study was carried out as a narrative review during November 2022. A thorough literature review was conducted on the following databases: PubMed, Scopus, SciELO, CINAHL, Web of Science, and ScienceDirect. The following parameters were assessed from the included studies: type of cholera vaccine, cholera symptoms, cholera treatment, effect of cholera on pregnancy, effect of cholera treatment on pregnancy, effect of cholera vaccine on pregnancy, risk factors for fetuses and neonates, and prevention of cholera. The authors independently extracted data from the 24 included studies.

Results

Cholera infection is a serious threat on pregnancy as it could lead to increased stillbirths and neonatal death. Fetal death was shown to occur mainly in the third trimester as most of the pregnant women infected with cholera had spontaneous abortions even after controlling for other confounding variables such as maternal age, dehydration level, and vomiting. Neonatal death was attributed mainly to congenital malformations and low Apgar scores with no improvements. Besides, cholera vaccines have shown to be safe in pregnancy and have proven to lower fetal and neonatal malformations among vaccinated compared to nonvaccinated pregnant women.

Conclusion

This narrative summarizes the different complications due to cholera infection in pregnancy. It also reviews the safety of cholera vaccine administration in pregnant women.

Update on CVD 103-HgR single-dose, live oral cholera vaccine

Cholera remains endemic in >50 countries, putting millions at risk, especially young children for whom killed vaccines offer limited protection. An oral, live attenuated vaccine - CVD 103-HgR (Vaxchora vaccine) - was licensed by the US FDA in 2016 for adults aged 18-64 years traveling to endemic regions, based on clinical trials in human volunteers showing the vaccine was well tolerated and conferred 90% efficacy within 10 days. The evidence base for Vaxchora vaccine has expanded with additional clinical trial data, in older adults (aged 46-64 years) and children (aged 2-17 years), demonstrating that the vaccine produces a strong vibriocidal antibody response. Over 68,000 doses have been administered in the United States, with no new safety signals. The dose volume has been reduced in children to improve acceptability, and cold chain requirements are less st ringent, at +2°C─+8°C. The vaccine has recently been licensed in the Untied States for children aged 2-17 years, in Europe for individuals aged ≥2 years, and for home administration in Europe. Next steps include a Phase 4 study in infants (6-23 months). Additional information is needed regarding duration of immunity, the need for and timing of revaccination, and efficacy data from lower-middle-income countries.

Cholera, the Current Status of Cholera Vaccines and Recommendations for Travellers

Cholera is endemic in approximately 50 countries, primarily in Africa and South and Southeast Asia, and in these areas, it remains a disease associated with poverty. In developed nations, cholera is rare, and cases are typically imported from endemic areas by returning travellers. Cholera is readily preventable with the tools available to modern medicine. In developing nations, cholera transmission can be prevented through improved water, sanitation, and hygiene services and the use of oral cholera vaccines (OCVs). For travellers, risk can be mitigated by practicing regular hand hygiene and consuming food and water from safe sources. OCVs should be considered for high-risk travellers likely to be exposed to cholera patients or contaminated water and food. There are currently three World Health Organization pre-qualified OCVs, which are based on killed whole-cell strains of Vibrio cholerae. These established vaccines offer significant protection in adults and children for up to 2 years. A novel live attenuated vaccine that provides rapid-onset protection in adults and children is licensed in the USA and Europe only. Live attenuated OCVs may mimic the natural infection of V. cholerae more closely, generating rapid immune responses without the need for repeat dosing. These potential benefits have prompted the ongoing development of several additional live attenuated vaccines. The objective of this article is to provide a general review of the current landscape of OCVs, including a discussion of their appropriate use in international travellers.