How different ‘suppression’ tactics could limit coronavirus deaths

Coronavirus-related deaths in Great Britain could vary in number dramatically depending on what type of suppression strategy the Government follows, according to the latest work by the Imperial College Covid-19 response team.

Suppressing the spread of the virus slows down transmission to very low levels – but its success depends on the scale of tactics adopted.

The Imperial College team modelled various suppression strategies to project the volume of virus-related deaths in Great Britain over a two-year period.

Assuming a transmission rate of two secondary cases for every one new case, the team found that doing no kind of suppression could lead to around 410,000 deaths – a number that rises to 550,000 were the transmission rate to jump to 2.6 secondary cases for every one new case.

But these numbers start to fall when different types of suppression scenarios are considered.

A combination of case isolation, home quarantine and social distancing could see total deaths fall to 47,000 under the two for one transmission rate.

This drops to 6,400 deaths for a combination of school/university closure, case isolation and social distancing, and to 5,600 if all four tactics are combined.

These projections are based on a level of 60 new Covid-19 cases diagnosed in intensive care units (ICUs) every week.

If this level rose to 400 cases a week, the projections change – with 26,000 deaths likely over two years, even with all four suppression tactics combined.

The figures change again under a transmission rate of 2.6 secondary cases for every one new case.

Here, Imperial College found that even with just 60 new cases diagnosed in ICUs a week, a combination of case isolation, home quarantine and social distancing could see total deaths of 110,000 over two years.

This falls to 20,000 deaths for a combination of school/university closure, case isolation and social distancing, and to 12,000 if all four tactics are combined.

But if the level of ICU cases increases to 400 a week, the projections suggest 48,000 deaths even if those four tactics are combined.

The Imperial College team conclude their report by saying a “minimum policy for effective suppression” is population-wide social distancing combined with home isolation of cases and school and university closure.

This has the potential to suppress transmission below the threshold of one secondary case for every one new case, which is required to rapidly reduce the number of incidents.