Tech to keep vaccines from heat damage

The significance of vaccines in enhancing child health cannot be overstated. Without immunisation, millions of children worldwide would die during infancy and never live up to their full potential.

Thanks to vaccines, the world was able to eradicate small pox that wiped away generations of mankind.

They have also contributed to the immense reduction in global child deaths whilst preventing birth defects and lifelong disabilities such as paralysis from polio.

In addition, the number of people suffering from preventable infectious diseases like measles, diphtheria and whooping cough has also gone down drastically.

It is for this reason that vaccines are considered as one of the greatest innovations in public health. Indeed, the World Health Organisation (WHO) statistics estimate that they avert an estimated two to three million deaths each year.

Despite their significance, the stringent storage requirements recommended for keeping vaccines safe and effective, pose continuous challenges to developing nations hence hampering access to vaccines for all children.

Most childhood vaccines are heat sensitive. This means that they have to be kept constantly cold – between two degrees and eight degrees – for them to work well. These conditions need to be maintained each step of the way – from the factory to the end user.

Although this is not a significant challenge in wealthy nations, it remains a big hurdle in developing countries like Kenya – particularly in hot, remote and isolated areas that lack reliable electricity for refrigeration.

Transporting vaccines to such places is also challenging, as the low temperatures have to be maintained at all times. This contributes to low immunisations rates in affected regions.

For decades scientists have been working round the clock to find solutions to this challenge. Their hard work is beginning to bear fruit.

Researchers from the Universities of Bath and Newcastle in the United Kingdom (UK) have discovered a new way of preventing the degradation of vaccines through heat.

When most childhood vaccines are exposed to temperatures above eight degrees Celsius, the proteins used to make them usually start to unravel, hence making the vaccines ineffective.

The researchers discovered that the damage could be prevented by encasing protein molecules in a silica shell.

This structure was found to remain intact even when heated at 100 degrees Celsius, or stored at room temperatures for up to three years.

This technique, known as ensilication, was first tested in research laboratories and found to work about two years ago. But its effectiveness in real life situations still remained unknown.

To unravel this mystery and find out whether the novel technique can prevent vaccines from degradation as they are transported to different locations, the researchers conducted a trial experiment.

They sent both regular and encased samples of the existing tetanus vaccine from Bath city to Newcastle city in the UK by ordinary post. This is a journey time of over 300 miles (482 kilometres), which by post takes a day or two.

When doses of the encased tetanus vaccine were subsequently injected into mice, an immune response was triggered. This showed that the vaccine was active.

On the other hand, no immune response was detected in mice injected with normal doses of the tetanus vaccine that were not encased. This indicated that the vaccine had been damaged in transit.

The results of this study, which have been published in the Scientific Reports journal, demonstrate the effectiveness of the new technology in real life transportation of goods.

“This is really exciting data because it shows us that ensilication preserves not just the structure of the vaccine proteins but also the function,” said Dr Asel Sartbaeva, the lead author of the study from the University of Bath’s Department of Chemistry.

Going forward, the researchers plan to create silica cages for other heat sensitive vaccines to enable all children globally to get required immunisations without having to rely on the cold chain distribution (requiring a vaccine to be refrigerated from the moment of manufacturing to the endpoint destination).

“The aim is to eradicate vaccine-preventable diseases in low income countries by using thermally stable vaccines and cutting out dependence on cold chain,” stated Dr Sartbaeva.

In Kenya, immunisation coverage is currently at 79 percent. However, this national figure hides regional disparities in the uptake of childhood vaccines.

For instance, whereas coverage is at a high of 90 percent in the Central region, the number of children that have received all basic vaccinations is only 51 percent in the North Eastern Region.

Aside from being characterised with high temperatures, most areas in North Eastern the region are remote and hard to reach. They also lack electricity.

Such areas would benefit immensely from heat stable vaccines that can withstand the hot climate and still remain effective.