According to a new online Covid-19 calculator, Wiltshire still has a zero per cent chance of becoming a hotspot.

The tool, developed by Imperial College London, predicts what local authorities could see Covid-19 spikes in the next two weeks using data on daily reported cases and weekly reported deaths and mathematical modelling.

The site also provides estimates for each local authority in England, Scotland and Wales on whether cases are likely to be increasing or decreasing and the probability of R(t) being greater than 1.

In the two weeks to September 20, the map showed Wiltshire had a zero per cent chance of seeing weekly reported cases rise above 50 per 100,000, thus becoming a hotspot.

In the two weeks to October 3, the situation will remain unchanged, the tool predicts.

However, some areas nearby will see their chances of becoming hotspots increase.

These include Test Valley (from 7 per cent to 19 per cent), New Forest (from 2 per cent to 9 per cent) and Mendip (from 4 per cent to 13 per cent).

The map uses daily cases data for all local authorities in England from the government website.

Weekly deaths data for all local authorities in England and Wales comes from the Office for National Statistics (ONS).

The predictions assume no change in current interventions, such as lockdowns and school closures, in a local authority beyond those already taken about a week before the end of observations.

Researchers also note that an increase in cases in a local authority can be due to an increase in testing, which the model does not currently account for.

It also assumes all individuals within each local authority are equally likely to be infected, so demographic factors such as the age structure of the population are not considered.