The disclosure by Boulle, who works at the University of Cape Town Centre for Infectious Disease Epidemiology and Research, came during a weekly news conference hosted by premier Alan Winde.
The epidemiologist said “recalibrations” by groups of modellers tracking the Covid-19 trajectory indicated that the pandemic's peak in the Western Cape was likely to be flatter, longer and later than previously predicted.
However, this did not affect the extent of the crisis the province was facing, he said.
“If the Western Cape were a country and we compared it to other countries, at this point globally we might be one of the countries with the highest daily mortality rates,” he said.
“Some of our most affected subdistricts have mortality of 600-700 deaths per million, and that is still rising.”
The eventual mortality rate could easily reached 1,500 per million, “which would take those communities into the realm of New York state, Madrid or Stockholm”.
As of Wednesday, Klipfontein - an area of 380,000 people who live in neighbourhoods such as Delft, Gugulethu, Nyanga and Manenberg - had 6,316 confirmed Covid-19 cases.
The number of cases per 100,000 people was 1,662 - the highest in Cape Town - meaning almost 17 people in every 1,000 have been infected. The subdistrict also has the highest per capita rate of active cases, about 400 per 100,000.