The Western Cape is expected to breach its intensive-care unit (ICU) capacity in early to mid-June, while Gauteng and the Free State are expected to follow suit in mid-July or later.
Professor Juliet Pulliam, a specialist in the modelling of infectious diseases, was speaking via an online talk hosted by the science faculty of Stellenbosch University this week.
Pulliam, director of the South
African Centre for Epidemiological Modelling and Analysis, provided an overview of how models can, and can’t, be used to better understand emerging diseases, with particular reference to model results for Covid-19 in South Africa.
She is a member of the South African Covid-19 Modelling Consortium. Its National Covid-19 Epi Model is a tool to improve resource planning.
On the question of “how long do we have to expand ICU capacity before current capacity is exceeded?” she said the approach was to compare detected cases on June 1 with predictions under an optimistic and pessimistic scenario to assess the current trajectory. Based on the current trajectory and long-term projections, the model will evaluate the likely time when capacity will be breached by province.
For the Western Cape under its current pessimistic trajectory, with 22 567 cases recorded on June 1, “we expect to be breaching ICU capacity in early June or perhaps as late as mid-June.
“And that is consistent with what’s been seen in hospitals. Certainly in the public sector, the ICU capacity has already been exceeded and they’ve been working hard to expand that capacity and working out ways to transfer patients to the private sector.
“The summary for most of the provinces is more on the optimistic side of things, but it’s worth noting that we’re still expecting bed capacity will be breached. It will just be later.
“The Eastern Cape, which is doing worse than pessimistic, is expected to breach in mid-June, while most of the other provinces will breach sometime in July, though it could be later for Gauteng and the Free State.”
The current trajectory for
Gauteng and the Free State is “better than optimistic”.
The next steps, she said, was the inclusion of local data on hospitalisations and deaths “to better parameterise the treatment and mortality pathways” as well as work accounting for excess mortality due to exceeding hospital capacity.
The limitations of the National Covid-19 Epi Model spanned that
projections at a population level
do not capture clustering of cases, such as funerals; the current model projects the total need for hospital and ICU beds and does not account for changes in population behaviour. Projections, she said, would improve with new data.
There is also uncertainty regarding “both the true scale and spatial distribution of cases as a result of changing testing criteria and coverage”, she said.
The Saturday Star