A letter written by the father of vaccination Dr Edward Jenner to a fellow physician who had supported his pioneering work is expected to fetch up to £8,000 at auction.

In 1798, Dr Jenner published his study of the cause and effects of the disease now known as cowpox and how it could act as a vaccine for the smallpox virus.

Four years later, he wrote to Dr John Glover Loy, a Whitby-based doctor, to thank him for his own work.

Dr Loy’s research had vindicated Dr Jenner’s theory that the origins of cowpox was a disease of horses referred to as “grease”, known as horsepox, and supporting the role of horsepox in the prevention of smallpox.

The letter, which is being sold by descendants of Dr Loy, will go under the hammer at Dominic Winter Auctioneers in South Cerney, Gloucestershire on June 16.

Dr Jenner writes that he is keen for Dr Loy’s findings to be read widely, especially in London, where it will be seen by his own critics.

“I know of no production on the vaccine subject which has afforded me more satisfaction, since it was first brought before the public, than yours,” Dr Jenner wrote.

“It contains the experimentum crucis and has effectually put a stop to the sneers of those little minded persons who think everything impossible which does not come within the narrow sphere of their own comprehension.

“I regret that your confirmation of the fact I had adduced, is not more generally known.”

The development of the smallpox vaccine led to the eradication of the disease worldwide by 1980.

“Edward Jenner letters rarely come up for auction and are always of interest and this one is expected to fetch over £5,000,” said auctioneer Chris Albury.

“To get one which concerns vaccination is ideal, but this letter also offers insights into Dr Jenner’s character and true feelings as he battled with the medical establishment while promoting his ideas.

Mr Albury said Dr Jenner’s ideas were received enthusiastically in some quarters, but they were not universally accepted and there were strong anti-vaccination feelings, then as now, for a whole variety of reasons.

“One can understand some of the anti-vaccination sceptics who were nonplussed by the idea of using cowpox pus to inoculate people against smallpox in terms of hygiene and its ‘unchristian’ practice coupled with distrust in medicine generally,” he said.

“The more common practice at the time was to use smallpox itself to inoculate against the disease, but the risks were great with a mortality rate of 2% and the added danger of creating local outbreaks and more transmitters of the deadly disease.

“Dr Jenner’s vaccination theories were proven right and by 1840 the British government banned the use of variolation – the use of smallpox to induce immunity – and provided vaccination using cowpox free of charge.”

The 18th century scientist discovered the vaccine for smallpox virus at his home in Berkeley, Gloucestershire.

Dr Jenner built a one-room hut in his garden to vaccinate people for free. He died of a stroke in his study in 1823.