Has SA missed its target this week for the lockdown to be eased?

One of government’s chief scientific advisers, Professor Salim Abdool Karim, revealed this week that it was likely he and his team of more than 40 experts would advise for the lockdown to be extended if the infection rate had not declined to a targeted level.

He was speaking to the country with Health Minister Zweli Mkhize and numerous other experts on Monday evening following a meeting of the National Command Council.

The professor focused on the coronavirus’ R0 rate, which is the basic reproduction number of an infectious disease. He said that if this rate could be shown to be below 1, meaning the disease was not spreading at an out-of control rate, then a decision could be considered to ease the current lockdown, which is one of the most stringent in the world.

He said that this meant that the average number of people getting the disease every day between 10 and 16 April would need to be less than 90.

The coronavirus is known to have a global R0 of between 2 and 3, so to limit it to less than 1 would be quite an achievement.

The current data

So how has South Africa performed on a daily basis between 10 April (last Friday) and 16 April (yesterday)?

On 10 April, Mkhize announced that the total number of confirmed infections in the country was at 2,003. By the evening of 16 April that figure had risen to 2,605. The average over those six days was therefore just above 100. If the jump from 9 April to 10 April (69 cases) is included in the calculation, the average comes down to about 96, but is still above the targeted number of less than 90.

10 April: 69 new cases

11 April: 25 new cases

12 April: 145 new cases

13 April: 99 new cases

14 April: 143 new cases

15 April: 91 new cases

16 April: 99 new cases

Total: 671, giving a daily average of 95,86.

If the advisory panel therefore decides to strictly apply their own guideline, this would suggest President Cyril Ramaphosa will be advised over the weekend to continue with a more stringent version of the lockdown, and not to ease too many of the current restrictions on movement and economic activity.

Government yesterday announced that the lockdown would be eased in stages, though local government minister Nkosazana Dlamini-Zuma and others were cagey about many of the exact details of what this would involve.

Karim said this week that the current flattening of the rate of infections appeared to be due to the lockdown implemented from 26 March. Prior to the lockdown, the country was on the same exponential growth curve as other countries. He compared South Africa to the UK, which had continued on an exponential curve after not implementing a hard lockdown.

When Karim spoke about the rate of infection – meaning how many people with the illness were infecting others – he said that in South Africa they had managed to keep it to about 1, meaning those with the illness were on average only infecting one other person, but that it was important to lower this figure even further.

He said the country had only delayed the apparently inevitable spread of the virus in any event.

“I have to tell you that as much as we have succeeded in stemming the flow of this virus, a success no one else has achieved, I have to tell you a difficult truth. The exponential spread cannot be escaped. Not unless we have some mojo that protects us that’s not present anywhere else on earth.

“As soon as we end the lockdown, we will have that high risk. We know that this virus can spread really fast. An infected person can infect two to three people.”

He said that the virus could therefore double in its spread every two to three days.

The government’s interventions had, however, successfully delayed the viral spread for now.

Flattening the curve

“Why is the delay important? Because if we allow it to grow unchecked we will see what we see in New York where the healthcare system is overwhelmed,” said Karim.

He added that by being proactive, community health workers could go into communities and diagnose people before they showed symptoms. He expressed hope that a vaccine would be available in a year or 18 months, but by then “our epidemic will be over”, though in the interim successful treatments could become available.

The professor said the coming week would be critical to see what the community rate of infection was. By 18 April (tomorrow), if community infection had been kept low, and the average variability had been kept to between 45 and 89, then “if we base it on that, we have a set of criteria: if the average is 90 between 10 and 16 April, then we need to keep the lockdown”.

He pointed out that it took about two weeks to really see the effect of any interventions because of how long it took for those with the virus to show symptoms, which was why the R0 rate and other data over this past week would be so instructive for how to deal with the lockdown by the end of the month.

If the average showed that the infection was moving at less than one person infecting one person (ie, an R0 of less than 1), then a decision could be taken to ease the lockdown.

“If we end the lockdown abruptly, we run the risk of undoing all we have achieved. We will put low and high risk people together.”

He said there would be a systematic easing of the lockdown instead, when eventually it does happen.

‘1 in 1000’

In an interview with News24 on Wednesday, Karim said: “Our challenge is to make the best advice available on the limited evidence that is available.

“Everything we’re doing is based on very little evidence relating to the coronavirus. Because it’s only really in the last four months that there is research being done and evidence being generated. So we have to draw on our experience from other viruses, from other epidemics and from what we have learnt over decades from dealing with viral diseases like this, and we are able to do that,” said Karim in praise of the experts on his advisory committee.

This is because the elements of a virus, and how it spreads, remain the same.

Touching on the contents of his earlier presentation, he repeated the purpose of a lockdown, in addition to outlining the ideal criteria under which it would end.

Since the main aim of the country’s lockdown period was to control community transmission, Karim believed that if there were more than 1 in every 1,000 people who had the virus, then the country should stay in a lockdown.

The professor admitted there was no perfect ratio in this regard but 1 in 1,000 seemed “fairly reasonable”.

He said he also based this number on the fact that it made it easier to glean the impact of infections in a population of more than 55 million people.

This was based on the approach taken by Chinese authorities in Wuhan – an approach Karim said had inspired South Africa’s Covid-19 response to some degree – and which was chosen from four options taken by countries throughout the world.

He listed them as the ostrich approach, the herd-immunity approach, the partial herd immunity approach and lockdown.

The first is named after an ostrich’s fabled tendency to bury its head in the sand and pretend things are not as bad as they are. He said this was the option taken by US President Donald Trump.

To illustrate herd immunity, Karim used measles as an example. Based on the world’s treatment of measles, he said that in order to achieve herd immunity, measles taught the world that one would have to immunise/vaccinate 95% of one’s population to protect the remaining vulnerable 5% of the population from infection.

“We don’t know what the herd immunity level is for the coronavirus. You have no idea how many people are going to have to get infected to protect the entire population.”

He listed the UK as a country that had tried this approach, which also did not appear to work.

Additionally, he touched on the idea of partial herd immunity where older people could be placed in lockdown while those under the age of 60 were allowed to continue their lives as normal to a point where enough people got the infection and built up some sort of immunity before older people could be allowed out of lockdown. Sweden had tried this approach and Karim said they now had the highest coronavirus death rate in Scandinavia.

From the experiences of those three countries, South Africa had decided to go with China’s approach of a hard lockdown instead, as it seemed to be the most effective of the four.

“It remains to be seen whether they [China] have herd immunity. In other words, it remains to be seen whether or not enough people got infected in Wuhan in the first epidemic to see whether or not everyone gets protected if the virus comes back. And it’s going to come back.”

As such, the committee was watching Wuhan closely in order to see how they fared.

“We will have some idea from Wuhan as to what herd immunity levels are going to be.”

The Chinese city Wuhan, where the coronavirus first emerged, raised its death toll by 50% on Friday, revealing the ground zero of the global pandemic had been much worse hit than Beijing had previously reported.

(Additional reporting, Kaunda Selisho)

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