As cholera cases rise, demand for vaccines still outpace supply: WHO

The demand for cholera vaccine continues to outpace supply, even as 24 countries have reported close to 200,000 cases this year, according to the World Health Organization (WHO).

Since January last year, 16 countries have requested 92 million oral cholera vaccine (OCV) doses, nearly double the 49 million doses produced during this period.

In March 2024, the WHO reported a shortfall in the global stockpile of OCV. Consequently, a single vaccine dose was recommended instead of the previous two-dose regimen.

The situation, however, has since improved. The stockpile exceeded the emergency target of five million doses in early June for the first time in 2024. As of 10 June 2024, the stockpile contained 6.2 million doses.

Currently, the world is facing the seventh cholera pandemic, which took off in the 1960s. Since 2021, there has been a spike in cases of cholera, a disease that spreads through water and food contaminated by Vibrio cholerae, a marine bacteria.

Further, in January 2023, WHO classified the global spike in cholera as a grade 3 emergency, an event requiring a major to maximal WHO response.

This created more demand for vaccines. More doses were requested for outbreak response between 2021 and 2023 than in the entire previous decade, according to the WHO. 

According to forecasts, global production capacity in 2024 could be 37-50 million doses. This will likely continue to be inadequate to meet the needs of millions of people directly affected by the disease, WHO noted.

WHO has prequalified three vaccines: Euvichol, Euvichol-Plus and Euvichol-S produced by EuBiologicals Co Limited, Republic of Korea.

In 2011, WHO prequalified Shanchol from India’s Shantha Biotechnics [acquired by Sanofi Pasteur] after it was licensed in India in 2009. In 2013, WHO created a global stockpile of cheap, safe and effective inactivated whole-cell OCVs. 

Shanchol was discontinued by Sanofi Pasteur in 2023, leaving EuBiologics as the only supplier.  

Cholera continues to wreak havoc despite being preventable and treatable. While the main solution to stop the bacteria in its tracks is to improve water, sanitation and hygiene (WaSH), vaccines help prevent, limit and control outbreaks in countries facing dire shortcomings in providing safe water, hygiene and sanitation, WHO noted. 

“OCVs can be used as a preventive tool in an endemic area before an outbreak occurs. This can be given when we spot warning signs like before monsoons, increased seawater temperatures, and increased sea levels,” Shanta Dutta, director, National Institute of Cholera and Enteric Diseases (NICED), told Down To Earth (DTE). The other approach, she added, is reactive, administered during an outbreak. “Preventive is better,” the expert highlighted.

Situation in India

Clinical trials conducted in India on OCV developed by Korea’s International Vaccine Institute, which negotiated an agreement between VABIOTECH and Shantha Biotechnics Private Limited, showed a protective efficacy of 65 per cent. No vaccine-related serious adverse events were reported.

It offers protection for up to five years. “By 65 per cent protection efficacy, we mean that out of 100 cholera cases in non-vaccinated people, only 35 cases occur among those vaccinated,” Suman Kanungo, scientist at NICED in Kolkata, told DTE.

Currently, NICED is working with the West Bengal state government and the Indian Council of Medical Research on a pilot study in the Bishnupur-II Block of South 24 Parganas district. “We will be testing the Euvicol vaccine on 50,000 people, including children. Two doses will be given two weeks apart,” Kanungo said.

The expert explained that the idea is to test feasibility, logistic challenges and post-intervention evaluation or the period after the intervention has been implemented or administered to the participants.

“We chose Bhishnpur-II because the bacteria is present in the ambient environment. The survey and preliminary work are done and we have identified five villages. We might start vaccination in July,” Atreyi Chakrabarti, deputy chief medical health officer of South 24 Parganas district, told DTE.

India has reported 565 outbreaks leading to 45,759 cases and 263 deaths from 2011 to 2020. From January 1 to May 26, 2024, India reported 1,320 cases and four deaths. 

“This represents only the tip of the iceberg, as cholera remains an under-recognised health issue and grossly under-reported in India,” reads a 2023 paper published in the journal Lancet Regional Health – Southeast Asia.