We all want instant solutions to the pandemic. For those US states which have recently suffered resurgence in fresh case numbers, there are many quick fixes being proposed which will somehow allow normal life to resume quickly, and schools to return this fall/autumn. This article looks at probable timescales, and what’s needed.
There’s now ample experience from Europe and New York City of the timecourse of measures to stop such runaway growth in fresh cases.
The pattern in fresh cases for New York City shows a peak in case numbers between 30 March and 5 April, from one to two weeks after the city went into lockdown. It then took eight weeks from the peak before the daily number of fresh cases fell below 500 per day, and a further two weeks before they finally dropped off.
In England, daily fresh case numbers rose exponentially from around 1 March until they exceeded 1,000 after 18 March. They then rose linearly until levelling off to a peak at around 1-10 April, two weeks after lockdown measures took effect. Since then they have been declining more slowly than the original rate of growth, reaching 500 fresh cases per day seven weeks after the peak, and taking a further two weeks to fall below 250.
Currently, states such as California, Texas and Florida are in a worse situation than either New York City or the whole of England were at their peak, often reporting as many as 10,000 fresh cases per day. Had they gone into full lockdown again last week, daily fresh cases would still be expected to rise for a further one to two weeks before reaching peaks of 12,000 to 15,000 fresh cases per day, perhaps even more in Florida. If the measures to prevent spread were effective enough to bring fresh cases down from those levels – roughly twice the peaks attained in New York City or the whole of England – then it’s unlikely that the daily rate would fall as low as 500 per day for at least another 12 weeks, and more probably towards 16.
Thus, if any of those states had applied a lockdown as complete as those in Italy, France, Spain or the UK last week, they would need to maintain that for at least 14 or probably 18 weeks before daily fresh case numbers would be likely to fall to around 500 per day. That’s at least three months, or the middle of October at the earliest, long after the intended date for re-opening schools.
The economic cost of such a full lockdown is very considerable, and there are several alternatives which are being proposed. I have been unable to find any evidence of a country or region comparable to those three states which has brought such high rates of Covid-19 infections under control without enforcing a sustained and complete lockdown.
In particular, some are advocating using the combination of distancing and universal wear of (mainly cloth) facemasks, or facemasks alone, without isolation of family units in their homes. Sadly, no other comparable country or region has attempted to bring high infection rates down using those measures alone, neither is there any evidence that they would be sufficient on their own to bring Rt values below 1, which is essential if the rate of new infections is to fall at all.
With Covid-19, there are no instant solutions. Vaccinations aren’t a few weeks away, but unlikely before next year, and may only confer transient immunity. Turning colossal infection rates into those small enough to re-open most businesses and schools is a long, hard and agonising process of isolation. Anyone who tells you that all you need is a facemask is making a false promise – exactly as happened in the pandemic influenza of 1918.