Vaccines

Diarrhea can be deadly, and children who suffer repeated infections can be left with lasting consequences. Fortunately, there are vaccines available for some of the deadliest causes of diarrhea, and other vaccines are in development.

Limited and inequitable access to these vaccines–and declining immunization rates resulting from the COVID-19 pandemic—leave many children vulnerable to diarrheal illness and death. As climate change impacts and urbanization grow, communities with poor infrastructure or that are particularly susceptible to natural disasters are at heightened risk for outbreaks of diarrheal diseases like cholera and the spread of rotavirus, ETEC, and Shigella. When illness does strike, because the specific cause of diarrhea is often unknown. Inappropriate antibiotics are often used for treatment, contributing to the global antibiotic resistance crisis.

Vaccines for rotavirus, the most common and deadly cause of severe diarrhea in young children, are available now and are making a significant impact in countries where they have been introduced. As rotavirus vaccines realize their potential, diarrheal disease burden caused by Shigella is projected to increase. Vaccines against ETEC and Shigella, the leading causes of bacterial diarrhea, are in development. And vaccines are under development for other diarrheal diseases like norovirus, paratyphoid, and non-typhoidal Salmonella. (Vaccines against other enteric diseases like typhoid are also available, and scientists are pursuing vaccines for additional diarrhea pathogens like norovirus, paratyphoid, and non-typhoidal Salmonella.)

Vaccines are also available to prevent cholera, a diarrheal disease commonly associated with outbreaks, which are increasing as climate change and urbanization degrade environmental conditions and sanitation systems.

Along with the impacts of COVID-19 on health systems and the decline of immunization rates, these global challenges must spur renewed action and investment.

Six pathogens (including rotavirus, ETEC, and Shigella), account for nearly 80 percent of diarrheal infections. Vaccinations against these pathogens could prevent hundreds of millions of deaths and prevent the kinds of repeated diarrheal episodes that keep far too many children from reaching their full potential. By preventing illness and the use and misuse of antibiotics, vaccines also help prevent the development of further drug resistance.

Rotavirus is a highly contagious virus that can cause diarrhea. It is often accompanied by vomiting and fever. If left untreated, it can lead to severe dehydration and death. While nearly every child in the world is at risk regardless of where he or she lives, children in poverty disproportionately die from rotavirus due to lack of access to emergency care. Even less-severe rotavirus cases can have a tremendous economic impact on families due to the high cost of treatment.

Unlike the bacteria and parasites that cause other forms of diarrhea, rotavirus cannot be prevented by improvements in water, hygiene, and sanitation—vaccines provide the best protection against it.

Rotavirus still claims the lives of more than 200,000 young children each year. Improvements to current vaccines and research on new-generation candidates are crucial to realize immunization’s life-saving potential.

In the countries where they are in use, rotavirus vaccines are saving lives and protecting child health. To date, more than 95 countries have introduced rotavirus vaccines into their national immunization program. However, fewer than 1 in 2 infants worldwide—over 75 million infants—still do not have access to them. Uptake in Asia, in particular, remains slow. We must do more to reach these children.

If introduced in all Gavi countries—including the remaining countries that have not introduced—rotavirus vaccines could prevent nearly 600,000 deaths and approximately US$900 million in treatment costs between 2018 and 2027.

The World Health Organization (WHO) recommends that all countries introduce rotavirus vaccines into their national immunization programs.

• There are currently four globally available vaccines against rotavirus.
• Vietnam and China each have nationally licensed rotavirus vaccines.

Countries can learn about available vaccines here: WHO: Rotavirus and assess and compare programmatic costs of different rotavirus vaccine products using PATH’s Rotavirus Vaccine Cost Calculator.

Learn more about vaccine introduction here: ROTA Council: How to Introduce.

Get more evidence on the impact of the rotavirus vaccine.

For qualifying countries, Gavi, the Vaccine Alliance provides rotavirus vaccine introduction support.

ETEC and Shigella are the leading bacterial causes of diarrhea among children under five years. Shigellosis and illness from ETEC usually follow the ingestion of contaminated food or water. Shigella can also be transferred by person-to-person contact. Compounding the problem, use and misuse of antibiotics for diarrhea strengthens the resistance of bacterial pathogens to drugs. Many species of Shigella have developed resistance to commonly used antibiotics, making cases more difficult and expensive to treat. Persistent bacterial infections lead to long-term consequences such as malnutrition and stunting.

As rotavirus burden decreases thanks to growing reach of the vaccine, recent data show an increase in the proportion of severe childhood diarrhea due to Shigella. The pursuit of Shigella vaccines is more urgent than ever. Vaccines against ETEC and Shigella are currently under development. PATH is collaborating with private- and public-sector partners to advance safe, effective, and affordable vaccines against these pathogens. If introduced in high-burden countries or sub-national regions, ETEC and Shigella vaccines are projected to have a significant public health impact.

Like other forms of diarrhea, cholera thrives in poor conditions is uniquely prone to outbreaks and epidemics because the bacteria that causes the illness (Vibrio cholerae) spreads rapidly. Families and children are most vulnerable in conditions of neglect, crowding, and poor sanitation. Our world faces many such struggles due to conflict, urbanization, and natural disasters.

As the global community addresses these challenges alongside the increasing insecurity of climate change, cholera outbreaks are occurring more frequently. This is straining an already limited global supply of cholera vaccines.

First made available in the World Health Organization’s global stockpile in 2013, oral cholera vaccine (OCV) has dramatically improved the ability to rapidly contain cholera outbreaks. OCV is safe, inexpensive, easy to deliver, and effective. But the global stockpile is extremely low, according to WHO. The need for increased donor investment in this critical solution is urgent.

Vaccines provide immediate protection during outbreaks, and protection lasts two to three years. Local investments in water, sanitation, and hygiene can provide long-term prevention.

Launched in 2017 by the Global Task Force for Cholera Control, the Global Roadmap to 2030 aims to achieve a 90% reduction in cholera deaths by 2030. The Roadmap outlines actions for countries, technical partners, and donors on three key areas: early detection and quick response; a targeted multi-sectoral approach to prevent cholera recurrence; and an effective mechanism of coordination for technical support, advocacy, resource mobilization, and partnership at local and global levels.