Digestive Health

01 September 2016

More efficient vaccine to beat diarrhoea deaths underway

Rotavirus vaccines are expensive and take time to produce. For developing countries, the fact that the vaccines need cold storage also presents a challenge.

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Globally every year nearly a quarter of a million children under the age of five die from diarrhoea caused by the rotavirus. Nearly all of these deaths are in the developing world.

Nigeria leads the pack

The rotavirus is a bug that results in acute gastroenteritis, diarrhoea and then severe dehydration. It can also cause fever and vomiting. Without proper medical attention it can be fatal.

Seven of the 10 countries that account for most rotavirus deaths are in Africa. Nigeria leads the pack, accounting for 14% of rotavirus deaths. The bug kills more than 31 000 children in Nigeria every year. Ethiopia, which has an under 5 population of 1.4 million, loses 7 000 children every year to rotavirus. They account for 3% of all rotavirus deaths globally.

There are no drugs available to treat rotavirus. It can be prevented by using a live, attenuated vaccine. These are a living version of a microbe weakened in the lab so it can’t cause disease. But they are expensive and need cold storage, a challenge in developing countries.

Currently an international organisation, the Gavi vaccine alliance, finances developing countries to procure rotavirus vaccines. But when this support eventually does fall away, the cost of marketed rotavirus vaccines will be too expensive for developing countries.

My colleagues and I are developing a vaccine that is cheaper and that won’t require refrigeration. It could also be manufactured in a fraction of the time currently required. We are in the process of testing the vaccine on animal models.

Traditional challenges

By the end of 2015 the rotavirus vaccine had been introduced in 81 countries. The number of deaths from the disease has been reduced by more than half. But the global coverage of the vaccine is still estimated at only 23%.

There are two main problems with the vaccine: cost and logistics.

Some vaccines are more expensive than others. A dose of the rotavirus vaccine costs US$5. This compares to the measles vaccine, which costs less than US$0.7 per dose.

In developing nations, the cost of rotavirus vaccines is borne by not-for-profit organisations and philanthropists who regularly step into the funding breach.

The logistics challenge is also huge. Live, attenuated vaccines need to be refrigerated to stay potent. Rotavirus vaccines therefore need a lot of refrigerated space. This requires electricity which is in short supply in many developing countries and is often not available in rural areas.

A new approach

Traditionally vaccines are produced through a technique in which cells are cultured. This is a complicated, slow and costly process.

But in the past decade the Australian Institute for Bioengineering and Nanotechnology has developed a groundbreaking microbial technology. The process involves virus-like particles assembling on their own outside the host cells. This means that they can be controlled easily, radically simplifying the manufacturing process.

This technology has been used to manufacture vaccines for influenza and group A streptococcus, a bacterium that causes a wide variety of infections including malaria. In both cases the cost of vaccines has dropped dramatically.

We are applying the same approach to develop a rotavirus vaccine that is made up of virus-like particles that display rotavirus antigens. The particles are not infectious but mimic a virus and stimulate the immune system which then learns to fight the real virus by practising on the virus-like particles.

Injected subcutaneously into mice, the particles induced high levels of antibodies.

Our latest findings open up the possibility of combining a vaccine against the virus that targets all circulating strains and reduces the economic burden of making it as well as storing it.

The next frontier

These are positive and encouraging results. But before any clinical trials can be done a series of safety and efficacy tests will need to be completed using appropriate animal models.

Once those are established we will move to clinical trials to generate sufficient efficacy and safety data.

Developing an effective rotavirus vaccine that is easier to manufacture and costs less will allow health authorities in developing countries to divert precious funds to other vital causes.

Read more:

1.5 million kids die from diarrhoea

Diarrhoea kills 2m kids per year

Infant diarrhoea: take action

Alemu Tekewe, PhD student at the Australian Institute for Bioengineering and Nanotechnology, Addis Ababa University

This article was originally published on The Conversation. Read the original article.

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The Conversation is a collaboration between editors and academics to provide informed news analysis and commentary that’s free to read and republish.

 

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Digestive Health Expert

Dr. Estelle Wilken is a Senior Specialist in Internal Medicine and Gastroenterology at Tygerberg Hospital. She obtained her MBChB in 1976, her MMed (Int) in 1991 and her gastroenterology registration in 1995.

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