Health Minister Dr Zweli Mkhize has explained how South Africa’s COVID-19 mathematical modelling has laid the foundation for the country’s response to the pandemic.
In a media briefing on Tuesday evening, Mkhize, along with a team of expert modellers assisting the National Department of Health, outlined the statistics used to inform how and where resources are distributed in South Africa’s fight against COVID-19.
“We are aware of a lot of modelers out there doing work. Some do it as largely academic work and with others, we engage them to say what have you got. We will not be able to say which model is right and which one is wrong. After you have more and more information, you are able to say you have refined the model and have gotten closer to what the reality might be,” Mkhize said.
“Earlier intervention is better in flattening that curve. We needed the time to be able to improve the health system capacity. More beds, more doctors, and more ICU beds had to be created. We needed to have a sense as to what the needs were going to be and what needs to be done before that situation arises.”
The models were developed by a consortium made up of organisations like MASHA, SACEMA, HERO and the NICD. There is extensive and ongoing input made to the models by clinicians, virologists, intensivists and epidemiologists.
One of the experts, Juliet Pulliam, said models are adaptable and are updated on a weekly basis.
“Models are tools that are adaptable, we use them as formal descriptions, a set of assumptions to the world. We have to recognise that there are certain things we can’t build in. We have seen in recent weeks a sharp increase of cases in the Western Cape and those types of events are essentially in some way random and not captured with the general population model,” she said.
“Models are tools that help you think of the future, they can help you understand how certain a future is…it is not a way of looking into the future like you would through a crystal ball.”
The research is made up primarily of two models, the National COVID-19 Epi Model and the National COVID-19 Cost Model. The Epi Model seeks to capture the transmission dynamics of COVID-19 at a population level over time. This takes into account the disease severity and the treatment pathway that patients may encounter.
This feeds into the Cost Model which represents the type, number and price of ingredients to cost reponses. Together, these two models inform the resource requirements and predict where gaps may arise.
The experts agreed that lockdown measures have worked in flattening the curve and delaying the peak of infection. They concluded that the extension of the lockdown to five weeks bought government critical time to ramp up community testing and prepare mitigation measures for the oncoming wave of infections.
They believe the peak of infection will come between July and August.