In the next four weeks, the number of Covid-19 cases nationally is estimated to top 400 000, and 7 400 deaths could occur, according to updated projections used by the government.

Updated projections by the South African Covid-19 Modelling Consortium (SACMC) was published by the National Institute for Communicable Diseases (NICD) on Wednesday, providing the first update to projections published initially on 19 May.

"The model projects that if testing patterns remain unchanged there may be more than 408 000 detected cases by mid-July. However, prioritisation of testing may result in a reduction in detected cases to approximately 133 000," the report, dated 12 June, reads.

News24 previously reported that Health Minister Zweli Mkhize confirmed that due to constraints on supplies of testing and extraction kits, testing strategy nationally would change to focus on patients who were hospitalised, those living in hotspot areas and healthcare workers.

The latest model used data from laboratory-confirmed infections until 5 June and a detailed set of parameter estimates.

"The cumulative number of deaths by mid-July is expected to be 7 440 (3 610-14 000)."

ICU bed capacities are expected to be exceeded in the Western Cape and neighbouring Eastern Cape by the end of June, according to the updated model.

But the SACMC urges caution when interpreting the projections.

The report reads: "The models have been developed using data that is subject to a high degree of uncertainty. All models are simplifications of reality that are designed to describe and predict system behaviour and are justified by the assumptions and data with which they are developed."

The May projections estimated that, by mid-July, the number of active symptomatic cases would be around 500 000 on an optimistic band, and 1.2-million on a pessimistic outlook, with estimated roughly 5 000 deaths by mid-July.

The SACMC is made up of key experts from several university-based institutions and is convened by Dr Harry Moultrie, a senior medical epidemiologist based at the NICD, the 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.