Outdated legislation is holding back ground-breaking vaccines from entering the market, experts say. Laws surrounding genetically-modified vaccines classify them as GM organisms – a separate category from other conventional medication – meaning that the new class of vaccines are subject to additional and costly bureaucratic processes.

The technology can help doctors respond to emerging medical threats such as the Zika virus and Ebola outbreaks. GM vaccines are also considered by the medical community as a great hope in battling diseases and conditions such as HIV, malaria and cancer.

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Conventional vaccines work by exposing someone to a different form of a disease in order to boost the production of antibodies and create a proper immune response for their body to defend itself. GM vaccines involve changing the genome (the DNA) of a small, safe part of a disease which would cause the immune system to develop a defence response to it.

Experts say genetically-engineered vaccines are safer and also effective against previously impervious diseases. Scientist are even considering GM technology to modify mosquitoes to stop the spread of Zika virus.

Oxford Professor Adrian Hill, who was part of the global effort to swiftly develop an Ebola vaccine, has said that policy is holding back research. He argues that both British and international regulators are classifying based on outdated legislation from many decades ago, a time when protocols in laboratories were more time-consuming and expensive.

"Because the vaccine is technically a GM organism, if we're going to vaccinate someone in our clinic we need special permission – not to protect the person from the dangers of the vaccine but to protect from the potential risks of that microbe getting out and contaminating the environment," he told the Times. "This is a nonsense. But you still have to go through committees."

UK researchers must abide by UK regulations, but the same policies are applied across Europe as well as internationally, limiting progress in GM vaccine technology. Last year, British pharmacy giant GlaxoSmithKline's experimental Ebola vaccine was approved for testing on human beings.

Bryan Charleston, of the Pirbright Institute, who will be speaking alongside Professor Hill at The Times Cheltenham Science Festival in June, said this made it a crucial tool against disease: "These complex diseases have sophisticated methods built up to prevent immune responses. So we have to start using more advanced techniques."