The UK Government is basing most of its current planning on the Imperial College London MRC Centre for Global Infectious Disease Analysis report issued last week.
This report describes two different strategies for coping; mitigation and suppression. Hitherto, we have been working on the basis of mitigation, but the Government's apparent change of direction on 16th March signalled a move towards the suppression strategy:
MitigationThis focuses on slowing but not necessarily stopping epidemic spread – reducing peak healthcare demand while protecting those most at risk of severe disease from infection.SuppressionThis aims to reverse epidemic growth, reducing case numbers to low levels and maintaining that situation indefinitely.
The conclusions of the report start at page 14:
Overall, our results suggest that population-wide social distancing applied to the population as a whole would have the largest impact.
To avoid a rebound in transmission, these policies will need to be maintained until large stocks of vaccine are available to immunise the population – which could be 18 months or more.
We estimate that for a national GB policy, social distancing would need to be in force for at least 2/3 of the time until a vaccine was available.
However, there are very large uncertainties around the transmission of this virus, the likely effectiveness of different policies and the extent to which the population spontaneously adopts risk reducing behaviours. This means it is difficult to be definitive about the likely initial duration of measures which will be required, except that it will be several months. Future decisions on when and for how long to relax policies will need to be informed by ongoing surveillance.
The majority of the effect of such a strategy can be achieved by targeting interventions in a three-month window around the peak of the epidemic. For suppression, early action is important, and interventions need to be in place well before healthcare capacity is overwhelmed.
We therefore conclude that epidemic suppression is the only viable strategy at the current time. The social and economic effects of the measures which are needed to achieve this policy goal will be profound. Many countries have adopted such measures already, but even those countries at an earlier stage of their epidemic (such as the UK) will need to do so imminently.