The virus is often carried by grey squirrels from North America,[2] which rarely die from the disease.

[5] However the mortality rate is still considered severe, and certainly capable of local extinction of red squirrels in areas that succumb to the disease.

[7] Most poxviruses are highly resistant to drying, which allows crusts to remain infectious for long periods of time.

The squirrelpox virus is regarded as a significant factor in the decline of red squirrel populations in the UK.

It is thought to be similar to a case of disease seen in East Anglian red squirrels at the turn of the 20th century.

In early 2023, over 11,000 people signed a petition to the Welsh Senedd calling for research into a vaccine to be restarted.