Major countries are now adopting radical social distancing policies, which may or may not be as effective as the lockdown in China’s Hubei province in late January. If they are, the Chinese experience suggests that global ex China daily new infections will peak in about 11 days, though at a significantly higher level than currently. Italy locked down earlier and could be a leading indicator.
Caveat: the following observations are made by an economist with no expertise in epidemiology.
The Wuhan lockdown was announced on 23 January and extended to other cities in Hubei province the following day. It is assumed here that the lockdown was effective from 25 January. Chinese daily new infections peaked 11 days later on 5 February (excluding a spike on 17 February due to a reclassification of existing cases), embarking on a trend decline thereafter. New infections rose by 730% between the start of the lockdown and the peak – see first chart.
The restrictions on travel and commercial / social interactions imposed in Italy and now being rolled out across Europe and in major US cities could be more or less effective in halting virus spread than the Chinese lockdown. The disease may have had greater momentum in China because of increased travel and social interaction ahead of and during the Lunar New Year holiday.
If an effective global lockdown began today (16 March), a repeat of the Chinese pattern would imply a peak in daily new infections on 27 March. A 730% rise from the current level would suggest peak infections of about 90,000.
The Italian lockdown was announced on 9 March. Assuming that it became effective the following day, peak daily infections might be reached around 21 March – second chart. The Italian numbers will be key for assessing the extent to which global experience is mirroring the Chinese pattern.
The Chinese peak on 5 February occurred just after a stock market low on 3 February. Several daily activity indicators (e.g. coal consumption at power plants, passenger traffic, property sales) bottomed out over the following two weeks.