Sugar technology keeps vaccines stable in the heat

British scientists have found a cheap and simple way of keeping vaccines stable, even at tropical temperatures, which they say could transform immunisation campaigns in the developing world.

The technology developed by Oxford University scientists and the privately owned Nova Laboratories would remove the need for costly infrastructure, like fridges and freezers that require power and can break down, and highly trained staff.

“Currently vaccines need to be stored in a fridge or freezer,” Matt Cottingham of Oxford’s Jenner Institute, who led the study, said in a statement. “You need a clinic with a nurse, a fridge and an electricity supply, and refrigeration lorries for distribution.”

“If you could ship vaccines at normal temperatures, you would greatly reduce cost and hugely improve access to vaccines. You could even picture someone with a backpack taking vaccine doses on a bike into remote villages.”

The team’s method uses a patented system from Nova called HydRIS and involves mixing the vaccine with the sugars trehalose and sucrose and leaving it to dry out on a filter or membrane.

As the water evaporates, the vaccine mixture turns into a syrup and solidifies on the membrane, preserving the active part of the vaccine in a kind of suspended animation and protecting it from harm even at high temperatures.

Flushing the membrane with water rehydrates the vaccine in a few seconds, the researchers explained in their study published in the Science Translational Medicine journal on Wednesday.

Cottingham’s team managed to store two different virus-based vaccines on sugar-stabilised membranes for 4 to 6 months at 45 degrees Celsius (113F) without the medicines being damaged.

They also found the vaccines could be kept for a year or more at 37 degrees Celsius with only tiny losses of vaccine.

“This is so exciting scientifically because these viruses are fragile. If we are able to stabilise these, other vaccines are likely to be easier,” said Adrian Hill of Oxford University, who also worked on the study.

Under the World Health Organisation’s (WHO) immunisation programme, nearly 80 percent of children are vaccinated against six killer diseases - polio, diphtheria, tuberculosis, whooping cough, measles and tetanus.

But one of the biggest costs of that programme is maintaining the so-called “cold chain” - ensuring vaccines are refrigerated all the way from the manufacturer to the child, whether in a developed nation or a remote village in Africa.

The WHO estimates that maintaining the cold chain costs up to $200 million a year in developed countries, increasing the cost of vaccination by as much as 20 percent.

In poorer nations, parts of the infrastructure can be missing or damaged, presenting a hurdle for effective vaccination schemes. Several teams of scientists around the world are working on ways to try to overcome the problem.

“If most or all of the vaccines could be stabilised at high temperatures, it would not only remove cost, more children would be vaccinated,” Hill wrote in a commentary about the study.

The work was funded by the Bill and Melinda Gates Foundation and funds from the Wellcome Trust. The team said the next step is to show the process can be scaled up for large production with standard or newly-licensed human vaccines.

SOURCE: Science Translational Medicine, online February 17, 2010.