Projections by a consortium of experts advising the government have been clarified to show that 12-million to 13-million Covid-19 cases could have cumulatively occurred in the country by November, of which only roughly 3.7-million will be detected.

News24 reported on Wednesday that the South African Covid-19 Modelling Consortium projected a figure of between 1- and 1.2-million cases and that the model was not a crystal ball prediction, but subject to change as more data became available.

During a further media briefing by the consortium and other modelling groups on Thursday, in conjunction with Health Minister Zweli Mkhize, it has now been clarified that the one-million cases are the expected number of active cases at the peak of the country's infection curve at that specific moment in time.

Peak infection is expected to occur between early-July (pessimistic, 1.2-million cases) and mid-August (optimistic, 1-million cases), according to the consortium's model.

The total number of detected cases would be around 3.7-million to 3.9-million cases by November, a report by the consortium published on the National Institute for Communicable Diseases (NICD's) website shows.

But the detection rate was dependent on the availability of testing.

Available ICU bed capacity was again highlighted as a concern. According to estimates, South Africa has around 3 300 ICU beds, which would quickly be overwhelmed.

News24 reported on Thursday that 25 ICU beds at Tygerberg hospital in Cape Town, the city's largest hospital, were already filled with Covid-19 patients.

As of Wednesday, the Western Cape had 6 157 active cases and 211 reported deaths – representing well over half of confirmed cases nationally.

The number of deaths expected remains around 40 000, cumulatively.

Of the projected 12-million to 13-million cases, 475 000 to 680 000 would require hospitalisation over time, Professor Juliet Pulliam, the director of the South African Centre for Epidemiological Modelling and Analysis, who is part of the consortium, said on Thursday.

The clarification means:

• Between June and November, 40 000 to 45 000 people could die from Covid-19, with nearly 500 deaths by the end of May.
• The total number of cases between June and November is expected to be between 12-million and 13-million, with around 50 000 cases expected by the end of May.
• Projected need for ICU beds is between 20 000 and 35 000 between June and November, and 500 by the end of May.
• General hospital beds required are expected to be between 75 000 and 90 000 between June and November, with just more than 2 000 beds required by the end of May.
• Provinces are expected to peak at different times, with varying levels of infection and deaths, but the national peak infection rate is expected around early-July to mid-August

The South African Covid-19 Modelling Consortium is made up of key experts from several university-based institutions and convened by Dr Harry Moultrie, a senior medical epidemiologist based at the NICD: Modelling and Simulation Hub Africa (Masha) from the University of Cape Town, the South African DSI-NRF Centre of Excellence in Epidemiological Modelling and Analysis (Sacema) from the University of Stellenbosch, Health Economics and Epidemiology Research Office (HE2RO), which is made up of experts from the University of the Witwatersrand and Boston University School of Public Health, based in the US.

Moultrie said the consortium would release updated models on a regular basis as new information and data became available.

Moultrie said during the previous briefing that the models would be updated regularly.

"These projections are subject to considerable uncertainty and variability. Estimates will change and improve as the epidemic progresses and new data become available," the consortium's report dated 6 May reads.

The report also clarified that the projections are based on the assumption that, after the lifting of the hard lockdown, Level 4 restrictions are assumed to be in place for one month, following which physical distancing would continue at a moderate level – but did not account for changes in behaviour across the population as mortality rates became clear.

Other models introduced

Other models from groups separate from the consortium were also briefly presented.

Ashleigh Theophanides, of Deloitte and Business South Africa, similarly projected 20 000 cases by the end of May, and three-million Covid-19 cases by December, with 120 000 hospitalisations during the peak infection curve in July.

Barry Childs, the healthcare committee chair of the Actuarial Society of South Africa (ASSA), briefly presented their projections, which are based on four scenarios. These scenarios take various factors of transmission rates of the virus, lockdown effects and non-pharmaceutical interventions into account at varying degrees.

The various ASSA scenarios differ in outcomes, but agree centrally, for the most part, on a projected number of deaths at just over 40 000.

"Much remains unknown," he said.