Mitigation or Suppression?


Imperial College London just  updated their report on interventions (other than pharmacological) to reduce death rates and prevent the health care system being overwhelmed. The news is not good.

They first modelled traditional mitigation strategies that seek to slow but not stop the spread, e.g. flatten the curve, for Great Britain and the United States. For an unmitigated epidemic they found you’d end up with 510,000 deaths in Great Britain, not accounting for health systems being overwhelmed on mortality. Even with a full optimised set of mitigations in place they found that this would only reduce peak critical care demand by two-thirds and halve the number of deaths. Yet this ‘optimal’ scenario would also still result in an 8-fold higher peak demand on critical care beds over available capacity.

Their conclusion? That epidemic suppression is the only viable strategy at the current time. This has profound implications for Australia which still appears to be on a mitigation path. First, even if we do our very best there will be a reduction of at best 50% in the death rate. This translates to on the order of at least 100,000 deaths. To put that in context that’s more than Australia lost in two world wars. The associated number of sick patients would undoubtedly also overwhelm our critical care system.

The only viable alternative Imperial College identified was to act to suppress the epidemic, e.g. to reduce R (the reproductive number) to close to 1 or below. To do so would need a combination of strict case isolation, population level social distancing, household quarantines and/or school and university closure. This suppression would need to be in place for at least five months. Having supressed it a combination of rigorous case isolation and contact tracing would (hopefully) then be able deal with subsequent outbreaks.

However Australia is not doing this, the Prime Minister has made this very plain, he’s not going to, ‘turn Australia off and then back on again’. We also seem to be underestimating the numbers (see this Guardian article on NSW Health’s estimates). So in the absence of the State Governments breaking ranks we are now on an express train ride (see chart below) to a national disaster of epic proportions. Jesus.