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Scientists develop new method to stop vaccines from degrading

By Nilima Marshall
A new method that stops vaccines from degrading in warm temperatures could help children in low-income nations receive life-saving inoculations, scientists have said.

Researchers from the universities of Bath and Newcastle believe they have found a way to make transportation and storage of vaccines safer without the need for refrigeration.

Their new method, known as ensilication, involves encasing the protein molecules in a vaccine in a non-toxic silica shell.

Study author Dr Asel Sartbaeva, from the University of Bath, said their process “preserves not just the structure of the vaccine proteins but also the function”, allowing the biological substance to work without temperature constraints.

At present, all vaccines follow a cold chain procedure which requires refrigeration at all times, from the manufacturing stage to the point of administration.

This temperature-controlled supply chain ensures vaccines are always stored between 2C and 8C.

However, despite best efforts, around 50% of vaccine doses are discarded before use due to logistical issues associated with temperature control, according to estimates from the World Health Organisation.

At higher temperatures, the proteins in vaccines can start to unravel making them ineffective.

Encasing these protein molecules in a silica shell enables their structure to remain intact – allowing the vaccines to be stored at room temperature for up to three years, the researchers said.

Dr Sartbaeva said: “We build our shell in a way so that it is completely encases the protein and stops the protein from unfolding – because it is this physical unfolding which leads to the breaking of the proteins inside the vaccines and it leads to the denaturation or spoiling of these vaccines.”

The researchers tested ensilicated and regular samples of the tetanus vaccine on mice and found the silica-coated vaccines triggered an immune response while the regular samples did not.

The team plans to work on developing thermally-stable vaccines for diseases such as diphtheria and whooping cough.

Dr Sartbaeva said: “Ultimately, we want to make important medicines stable so they can be more widely available.

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

The findings are published in the journal Scientific Reports.
(PA)