Scientists have warned that an antibiotic-resistant strain of the bubonic plague could emerge and are developing a vaccine for the disease that has killed as many as 200 million people throughout history.

The plague is a bacterial infection caused by the Yersinia pestis microbe and can be treated with antibiotics, but there is currently no vaccine approved for use.

The potential new vaccine is being devised by the team behind the Oxford/AstraZeneca Covid-19 jab as there currently isn't one in the UK.

The Oxford team already completed a trial of the vaccine, begun in 2021, on 40 healthy adults, which concluded that it's safe and able to produce an immune response.

Professor Sir Andrew Pollard, director of the Oxford Vaccine Group, said the results of the first trial are due to be peer reviewed within weeks, with more trials expected in the future.

He told The Telegraph: "There are no licensed plague vaccines in the UK. Antibiotics are the only treatment. There are some licensed vaccines in Russia.

"The risk in the UK is currently very low. Previous historical pandemics that had high mortality were associated with initiation from fleas on rodents but were driven by person to person spread."

The bubonic plague killed as many as 50 million people across Europe in the 14th century - 50% of its population - in what's known as the Black Death, one of the most fatal pandemics in human history.

Government military scientists have also called for a bubonic plague vaccine to be approved and manufactured in bulk because the disease still exists in some parts of the world, which could create the "potential for pandemic spread".

Scientists at Porton Down’s Defence Science and Technology Laboratory (DSTL) added that vaccines for the bubonic plague are of utmost importance because they will help "prevent future disastrous plague outbreaks".

They warned of a "demonstrable" risk of the bug evolving, with antibiotic-resistant strains having already been discovered in Madagascar and Peru. They also said antimicrobial resistance is compounding the risk of an outbreak, making the plague harder to treat.

The bubonic plague is carried by fleas who contract the bacteria from rodents and transfer it to humans they bite. Symptoms include a fever, headache, chills, and weakness and one or more swollen, painful lymph nodes, called buboes.

The bacteria can spread to other parts of the body if the patient isn't treated with antibiotics. The mortality rate for bubonic plague is between 30-60% if left untreated, but antibiotics can bring this down to 1-15%.