Devising a viable global strategy to combat Cholera

Since mid-2021, the world is facing an acute upsurge of the 7th cholera pandemic characterised by the number, size and concurrence of multiple outbreaks, the spread to areas free of cholera for decades and alarming high mortality rates. Based on the current situation and lack of vaccines and other resources, the World Health Organisation (WHO) assesses the risk at the global level as very high.

For reasons not yet fully understood, beginning in 2022 the world experienced an unprecedented surge in cholera outbreaks as characterised by the number, size and concurrence. Cholera is an acute, rapidly dehydrating diarrheal disease transmitted through water or food contaminated with the bacteria Vibrio cholerae O1. It is a disease of poverty, primarily affecting people living in areas without access to safe drinking water and inadequate sanitation.

The global burden of cholera is not fully known because of under-reporting, with some affected countries not reporting cases at all to avoid the stigma. One study estimates 1.3 billion people are at risk for cholera in a total of 69 endemic countries, with 2.86 million cholera cases and an estimated 95,000 deaths annually. Most of the global burden is in sub-Saharan Africa (60 per cent ) and South-East Asia (29 per cent ).

In January 2023, WHO declared cholera to be a grade 3 global emergency, the highest risk level. As of March, there were 24 countries reporting outbreaks, a number expected to increase as most countries are not yet in the high transmission season. The Steering Committee of the Global Task Force on Cholera Control (GTFCC) issued a statement that climate change multiplies the risk of cholera around the world, and the upsurge beginning in 2022 may be the new normal.

Unfortunately, the current global supply of vaccines is insufficient to meet the ongoing surge in outbreaks. As a result of the strained global cholera vaccine supply, in late 2022, the WHO International Coordinating Group (ICG), the body which manages emergency supplies of vaccines, temporarily suspended the standard two-dose vaccination schedule in cholera outbreaks and recommended a single dose instead. This strategy, while expanding the coverage of vaccines to a larger population, may be associated with reduced protection in young children.