[EXPLAINER] How Covid-19 modelling in South Africa works
When exactly is the Western Cape's infection rate reaching its peak and why are we hearing conflicting things? How does a coronavirus vaccine work? Epidemiologist Dr Jody Boffa explains.
When you create a model it is more of an art than a science - because you're taking data that you have.Dr Jody Boffa, Epidemiologist - Centre of Rural Health
For example, roughly 13% of South African adults have diabetes. Information from China had indicated that diabetics were more severely affected by Covid-19 so that information would then be added to the model.
This then indicates how those South Africans may be affected by the virus.
She says all these factors such as HIV, TB, and other comorbidities are added to the model.
You make guesses. You say here's how I think it will affect people with HIV, here's how I think it will affect people who are on ARVs, and here's how I think it will affect people who aren't. Here's how I think a lockdown will affect how many people are passing it on,Dr Jody Boffa, Epidemiologist - Centre of Rural Health
Modelers are making educated guesses and the inputs are constantly changing, she says.
So for example, a tight early lockdown might flatten the curve and then change what the model might look like.
You are putting in these assumptions and trying to recreate the amount of disease that is actually happening in society, and as those numbers shift and as more data comes in about how people are responding to the disease and spreading it, you change the assumptions to fit what the curve is doing.Dr Jody Boffa, Epidemiologist - Centre of Rural Health
This is how the modellers then determine when the peak will occur, she explains.
But how people respond to models is also something that cannot always be determined and as predictions of second and third waves are being reported in Europe, Dr Boffa says this continues to be 'a moving target.'
Dr Boffa emphasises that she is not involved in creating models so she does not want to make a clear prediction about the Western Cape peak dates that have been put forward.
But I suspect, because of our numbers, that probably end of July, early August is still Cape Town's first peak, and hopefully the only peak.Dr Jody Boffa, Epidemiologist - Centre of Rural Health
Trying to predict the rest of the country's peaks is determined by a number of factors.
It depends on the density of the population, comorbidities in the population, the ages of the population.Dr Jody Boffa, Epidemiologist - Centre of Rural Health
Listen to Dr Boffa below:
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