The Univeristy of Melbourne The Royal Melbourne Hopspital

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06 Jul 2020

Setting it Straight: Lessons learned from the first six months of COVID-19 – part one

Setting it Straight - Issue #14

As of 29 June, 2020, the World Health Organization (WHO) had, since January, recorded 10,021,401 ‘official’ cases of COVID-19, with 499,913 deaths globally. These numbers are certainly too low. ‘End of life’ is unmistakeable, so those counts may prove to be no more than two-fold out when we later see annual excess death statistics. But case numbers must inevitably reflect differential capacities to identify asymptomatic and mild infections by expensive PCR testing.

Until we have reliable, cheap serological assays that can be used at very large scale to detect the antibody ‘footprints’ of past infection, it is possible that the real ‘case numbers’ globally could be as much as 5 to 10-fold higher than the WHO figures. Following the extreme ‘10x-too-low’ scenario, a simple calculation tells us that 98 per cent of the global population is still vulnerable. Most epidemiologists think that ‘herd immunity’ should cut-in for COVID-19 when about 60 per cent of people have been infected. Some regions, like Brazil, where there has been minimal intervention by government will hit that earlier than others. Such ‘natural experiments’ are being closely watched. But it’s obvious that, for many countries, there is a way to go. This may only come to an end for most with the roll-out of effective vaccines to boost ‘herd immunity’ across the planet.