Covid-19: Joburg’s central suburbs hardest hit, geo-mapping shows lockdown contained initial spread to cities

Geo-mapping of 1 082 coronavirus cases in SA shows the lockdown has, in large parts, succeeded in containing Covid-19 to our cities, where patients first imported the virus to from abroad.

Johannesburg's predominantly affluent suburbs in Sandton, Randburg and surrounding areas, show the highest concentration of cases in the city, which is the epicentre of the outbreak in the country.

Gauteng tops the list with the highest number of cases per province, followed by KwaZulu-Natal.

The geo-mapping News24 has seen formed part of a presentation to the parliamentary health portfolio committee by the acting director general for the Department of Health, Anban Pillay, on Friday.

The presentation is the most detailed official analysis yet of the Covid-19 situation that has been made public since the first infection was reported on 5 March in Hilton, near Pietermaritzburg in KZN.

Durban's central suburbs of North and South Beach show cases radiating to neighbouring areas.

In Cape Town, cases are clustered in the city bowl – Green Point, particularly, and a second cluster is seen in the suburbs of Newlands and Claremont and nearby Rondebosch and Kenilworth.

The maps, which represent around half of the confirmed Covid-19 cases in the country, show how cases increase in frequency in densely populated areas, an expected characteristic of an infectious respiratory disease such as Covid-19.

On Monday evening, Health Minister Zweli Mkhize announced that there were 2 272 positive cases and 27 deaths.

Some smaller clusters, News24 understands from an analysis of the maps, are around hospitals. But so far, the number of confirmed cases far outweighs the number of hospitalised patients, many of whom would be self-isolating in their homes.

Cases become less frequent the further removed from metros which is significant evidence of case importation – the largest clusters are in cities with international airports.

Imported

According to Professor Cheryl Cohen, a key epidemiologist involved in the country's response to the outbreak who works for the National Institute for Communicable Diseases, South Africa's early outbreak was mostly as a result of travellers who imported the virus from the US, the UK and Europe and those they infected in turn.

The early sharp rise in cases in SA was therefore more a reflection of the exponential rise in cases in those countries.

Last week, Cohen warned the epidemic was evolving, changing to local transmission at a low level – people unknowingly infecting their families and contacts.

"If we hadn't had a lockdown, local transmission may have taken off more and also importantly, part of what the lockdown was designed to do was to stop people moving from Gauteng and KZN to other parts of the country…and feeding it to other parts of the country," Cohen told News24 during an interview on Thursday.

READ | NICD's top epidemiologist: How the Covid-19 pandemic is evolving and why we should be concerned

"We expect the lockdown will have damped the cases down and that will have stopped the spread to other parts of the country. But there will be a delay of maybe two weeks to see that, so it may be having some impact on the numbers. But you know, it may not be. The low numbers are partly because of the travel ban and also because transmission has been slowed; but we know that it's essentially a calm before the storm," she said.

Other key findings in Pillay's presentation include:

• In a worst-case scenario, Gauteng would see over 1.5 million Covid-19 infections at the end of winter, followed by KwaZulu-Natal with one million;
• The country has less than half the number of ventilators needed to deal with peak infection. Public and private hospitals currently have a total of 3 216 ventilators, compared to the 7 000 we need, and;
• The country currently has 4 909 critical care hospital beds available, but the need for beds in intensive care units could exceed 14 700 at the highest level of infection.

Only "severe to critical Covid-19 patients" will be treated at hospitals, while "mild to moderately infected patients" will be accommodated at field hospitals where basic medical care will be provided. 

The government's "readiness for worst case scenario" plan was informed by research from UCT's Modelling and Simulation Hub Africa. According to this scenario, if the lockdown was suspended this Thursday after three weeks, the peak would have hit the country around 18 August.

With no lockdown, South Africa was estimated to reach its peak coronavirus infections in July with an accompanying overwhelming number of people needing urgent healthcare. A five-week lockdown, that has paralysed the economy, is buying the government two more months to prepare for a flooding of hospitals at the end of winter.

Other provinces show medium sized outbreaks, also concentrated mostly to cities including Bloemfontein in the Free State:

In Mpumalanga, Limpopo, the Northern Cape, the Eastern Cape and the North West, cases are scattered few and far between: