Comparison of different exit scenarios from the lock-down for COVID-19 epidemic in the UK and assessing uncertainty of the predictions

Anatoly Zhigljavsky; Roger Whitaker; Ivan Fesenko; Yakov Kremnitzer; Jack Noonan

Let us now consider more informative scenarios when x = 0.95 and x = 0.97; that is, when the lock-down is made early, see x = 0.95 and x = 0.97 with a peak at around 2 months after the first one, and the second peak could be higher than the first one. This can be explained by observing that, even after 2 months of an epidemic with large x, even with lock-down and strong isolation of the group G and relatively small reproductive number (recall R 2 = 2), there is still a very large proportion of non-immune people available for the virus; a large part of these people is going to be infected even with smaller reproductive number. This prolongs the epidemics. Expected deaths toll for x = 0.95 is 13.8(5.5+8.3)K and for x = 0.97 it is 13.4(5.7+7.7)K. These numbers are naturally lower than 15(5.2+9.8)K for x = 0.9 but the difference is not significant. Figures 16-19 and the discussion above imply the following conclusion. Conclusion. A lock-down at an early stage of an epidemic (unless it is a very strict one like in Wuhan) is not a sensible decision in view of the economic consequences of the lock-down and the measures required for all the remaining (much longer) period of the epidemic. Moreover, in the case of an early lock-down, the second wave of the epidemic should be expected with a peak at around 2 months after the first one. In Figures 18 and 19 , we use x = 0.97 and x = 0.9. Expected deaths toll for x = 0.97 is 13.8(5.7+8.3)K. This is naturally lower than 15(5.2+9.8)K for x = 0.9. This is related to the fact that we isolate people from group G much earlier.