Assessing the feasibility, impact, and enabling factors for successful adoption of controlled temperature chain delivery for oral cholera vaccines in field settings

In Zambia’s remote border communities, getting cholera vaccines safely from storage to households is a race against distance, heat, and limited infrastructure.

Typically, vaccines are delivered using a cold chain that requires maintaining temperatures between 2–8°C, necessitating refrigerated transport vehicles and cold storage containers with ice packs during vaccine distribution. However, Euvichol-Plus® OCV has been approved safe for use under controlled temperature chain conditions, which allow the vaccine to be exposed to higher temperatures (up to 40°C) during the ten days prior to administration.

To assess the feasibility, acceptability, impact on vaccine uptake, equitable access, and programmatic efficiency of delivering the vaccine through a controlled temperature chain, the International Vaccine Institute’s project, Implementation Research on Controlled Temperature Chain for Oral Cholera Vaccine (OCV) in Zambia, is evaluating this approach in field conditions. This delivery enables the World Health Organization-prequalified OCV to reach communities safely during the final stage of delivery.

The controlled temperature chain delivery method, which eliminates the cold chain requirement, offers the possibility to enhance “last-mile” delivery and outreach, improve programmatic efficiency, access, and equity in vaccination campaigns, and strengthen health security, helping ensure vaccines make it to even the hardest-to-reach communities.

A first-of-its-kind collaboration for IVI and Zambia

This project, led by Principal Investigator Dr. Se Eun Park, is supported by Gavi, the Vaccine Alliance and is carried out in close collaboration with the Government of Zambia—Dr. Guissimon Phiri, Site Co-Principal Investigator at the Ministry of Health, as well as the Zambia National Public Health Institute.

“This initiative marks IVI’s first Gavi-funded grant, our first standalone research collaboration with the Zambian government, and IVI’s first implementation research and project on the combined theme of vaccine access, equity, and delivery strategy,” said Dr. Jessica Cowden, Deputy Director General of the Clinical, Assessment, Regulatory, Evaluation (CARE) Unit at IVI.

Two delivery approaches, one goal

The study includes a two-dose preventive OCV mass vaccination campaign delivered through two different approaches: controlled temperature chain delivery versus standard cold chain delivery.

Vaccination teams were assigned to either the controlled temperature chain or standard cold chain. They administered two doses of Euvichol-Plus® OCV to approximately 100,000 individuals aged 1 year and older (50,000 people by vaccination teams in each arm) living in Chienge District in Zambia, one of the most remote areas of the country, located in Luapula Province bordering the Democratic Republic of Congo. Both rounds of the preventive OCV campaign were successfully conducted in November and December 2025.

Reaching households in one of Zambia’s most remote districts

During each round of the preventive OCV campaign, vaccination teams and study enumerators collected field data on vaccination rates, temperature and vaccine vial monitoring, and key indicators of vaccination activities including vaccine preparations (in controlled temperature chain versus standard cold chain), administration, handling, and storage.

In the study target areas, vaccination teams operated through door-to-door outreach and fixed posts to provide opportunities for those missed at home to be vaccinated. Vaccines were carried in portable vaccine carriers or containers without ice packs as part of the controlled temperature chain approach, with vaccine conditions closely monitored prior to each administration using peak temperature threshold indicators, vaccine vial monitors, and controlled temperature chain expiry dates.

Collecting evidence from the field

Immediately following the vaccination campaign, a survey and in-depth key informant interviews were also carried out to capture the experiences of frontline immunization officers on using the controlled temperature chain approach for the first time in an OCV campaign. An OCV coverage survey was carried out in randomly selected households in the vaccination target areas to generate data on OCV coverage estimates, as well as knowledge and health-seeking behavior related to cholera.

Following the successful completion of the preventive OCV campaign and data collection, the study team is currently working on data analysis.

Informing future vaccine delivery

Cholera is a severe and life-threatening disease, which can cause death within hours due to severe dehydration from acute watery diarrhea if not treated properly.

“IVI has been working together with our vaccine manufacturing partners such as EuBiologics to increase the OCV supply in the global stockpile to support countries with endemic and epidemic cholera,” said Dr. Julia Lynch, Senior Director of the IVI’s Cholera Program. “Access to cholera vaccines saves lives and helps prevent the spread of the disease, and this controlled temperature chain implementation research will contribute to understanding the value of innovative vaccination strategies in areas with cold chain challenges.”

Principal investigator for the project, Dr. Se Eun Park, said, “We were able to conduct this implementation research thanks to Gavi’s support and the Strategic Advisory Group of Experts on Immunization (SAGE)’s acknowledgement of the public health benefit of Euvichol-Plus® OCV under controlled temperature chain conditions (for a maximum of 10 days in ambient temperatures not exceeding 40°C).”

“The Global Task Force on Cholera Control OCV Working Group also cited the controlled temperature chain as one of the priority research agendas,” Dr. Park continued. “Our study findings will be discussed with our partners in Zambia and disseminated to the wider global health research community to share experiences and voices from the frontline healthcare workers on the controlled temperature chain approach for OCV. We also aim to draw lessons learnt for policy implications of potential future applications of the controlled temperature chain strategy for improved vaccine access and efficiency in immunization programs in resource-constrained settings.”

This project is being conducted in collaboration with the Zambia Ministry of Health, Zambia National Public Health Institute, and Zambia Statistics Agency, with technical and advisory support from WHO headquarters, the Global Task Force on Cholera Control, and WHO’s Africa Regional and Zambia Country Offices.

Published: 2 February 2026