Oral cholera vaccine safe without refrigeration, finds icddr,b’s study

The affordable oral cholera vaccine (OCV) Shanchol™ is still safe and stimulates significant immune responses even when stored at higher temperature, a recent icddr,b study conducted in Bangladesh has shown.

These findings imply that Shanchol, the first licensed OCV developed by the International Vaccine Institute (IVI), maynot need to be refrigerated during its distribution (‘cold chain’ storage) – a stringent requirement that would limit Shanchol’s use in resource-poor settings such as Bangladesh.

Child being fed Shanchol vaccine. Photo: Shumon Ahmed / icddr,b


Published in the journal Vaccine, the icddr,b study tested the ability of Shanchol to stimulate immune responses having been stored for two weeks under standard cold conditions (2–8°C) or at 25oC, 37oC or 42oC. Storage at higher temperatures had no negative impact on the vaccine’s ability to stimulate protective immune responses or its safety.

Without the need for cold storage, the vaccine would be easier to distribute, vaccination costs would be lower and major logistical challenges to vaccine delivery would be removed.

Dr Firdausi Qadri, the icddr,b emeritus scientist who is coordinating cholera vaccine studies, commented: “This is the first report to show Shanchol’s stability at elevated temperatures and that its safety and immunogenicity profiles are not altered by high temperatures of storage.” A vaccine’s immunogenicity is its ability to induce an immune response in the body.

Over the last 8 years, Dr Qadri and her team have been working on different aspects of this OCV and have facilitated studies that have utilised over 500,000 doses of this vaccine in Bangladesh.

“These studies have generated encouraging data on feasibility and effectiveness of Shanchol when used in Bangladesh in collaboration with facilities of the EPI of the Government of Bangladesh,” says Dr Qadri.

However, she added, the OCV’s implementation in cholera-endemic countries could be made simpler and used more widely if stringent cold chain requirements could be avoided.

Dr Qadri expects that this new information about Shanchol’s thermal stability will influence global policies for use of the vaccine stored at higher temperatures than the cold chain required at present.

Shanchol vaccine. Photo: Shumon Ahmed / icddr,b

Shanchol proved highly effective when used during cholera outbreaks in different countries including Guinea, in West Africa in 2012. With the vaccine having proven effective across the world, the WHO began stockpiling Shanchol in 2013.

In Bangladesh, an earlier study by icddr,b conducted in 2011 showed that mass vaccination with Shanchol could be feasibly delivered to a high-risk endemic population through an existing national immunisation delivery system employed by the government.

At that time, the government provided cold-chain-related support at no cost to the project funded by the Bill and Melinda Gates Foundation. The recent icddr,b study now shows that Shanchol could be distributed without cold-chain support.