UK Covid-19 infection peak may have fallen before lockdown, new analysis shows – Professor Simon Wood, University of Bristol

By simply separating out weekly reporting variability, the long-term death rate profile becomes clear, and its peak can be located with confidence. Using the distribution of times from disease onset to death, it is possible to extend the model to infer the time course of fatal infections required to produce the later deaths. Because of the wide variability in onset to death times, a quite sharply peaked infection curve produces a death curve that declines only slowly. The inferred infection curve peaks a few days before lockdown, with fatal infections now likely to be occurring at a much-reduced rate.

Diagram shows the inferred time course of the number of fatal infections, where day 0 is March 13th. The continuous curve is the median estimate. The dashed curves delimit 80% and 95% credible intervals. The vertical grey line shows day of lock down. The overlaid scaled bar chart summarizes the probability distribution for the day of the infection peak.