The SA lockdown can be eased if the infection rate is brought below 1 – expert

Following a meeting of the National Command Council on Monday, President Cyril Ramaphosa mandated Health Minister Zweli Mkhize to hold a live engagement online to deal with technical aspects relating to the Covid-19 response.

The minister said on Monday that the president had asked him to take the public into government’s confidence on the decisions being taken to combat the Covid-19 outbreak.

This meeting, organised from Durban, was joined by several experts on Covid-19.

The minister said at the start of the engagement that the current stats on the outbreak were that there are now 2,272 confirmed cases in the country, a jump of 99 cases. There have been an additional two deaths, a 68-year-old male from the Western Cape and a 57-year-old male from Gauteng who passed away in ICU. This takes the total tally of deaths to 27.

More than 83,660 tests have been done. More than 438,000 screenings have been done. There are 10,654 tracers on the ground.

Prof Salim Abdool Karim said in his presentation that the first infections probably occurred in November in China, although the first recorded cases were in December. It probably originated from pangolins at a seafood/wet market in Wuhan, where the zoonotic virus jumped to humans.

The key element of the professor’s presentation centred on the R0 rate, which is the basic reproduction number of an infectious disease. He said that if this rate could be shown to be below one, 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.

Karim said that the current decrease in 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, but this line flattened from 26 March. He compared South Africa to the UK, which continued on an exponential curve. The UK did not implement a hard lockdown.

“Why is South Africa not on the expected Covid infection trajectory?”

He pointed out that South Africa’s curve was unlike most others, and South Africa compared favourably to countries that had turned the tide such as Singapore and South Korea.

South Africa was unique, though, he said. “No other country has reached that point of plateauing.”

Karim said that possible explanations were that South Africa was simply not testing enough, which he said was not borne out though. The other view was that the country was supposedly not testing people in poor areas enough, but he pointed out that the National Health Laboratory Service had increased its testing in these areas just when the graph started to plateau.

He said the plateau was “most likely due to some genuine effect”, pointing to the success of the initial lockdown.

‘Three waves’

The professor then explained that there would be three waves of infection. The first wave was the introduction of the virus into the country from international travellers.

“The travellers then interact with people: at home, at work, at hospitals and clinics.” He said that these people they then infected became part of the second wave of locally transmitted infections. They would then become part of the third wave of generalised community infections, which normally show exponential growth once infections reach about 100 people.

However, that wave did not increase to out-of-control levels of widespread community infections, said the prof.

He pointed out on one slide how the South African epidemic had been following the UK’s graph (as an example) closely until the lockdown kicked in.

“Even if you take the most successfully controlled epidemics, South Africa is unique. We just are not seeing that wildfire spread that we expected. The shape of our curve is quite different,” said Karim.

One of Prof Karim’s slides.

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 one, meaning those with the illness were on average only infecting one other person.

“Each infected person becomes a dead end.”

He also said that they were not seeing many examples of people with very bad symptoms either, and the death rate had also been kept relatively low.

The ‘three hubs’ and beyond

The cities of Johannesburg, Cape Town and eThekwini were the centres where the virus could spread from most rapidly. He said that since there was no vaccine, no immunity and no treatment, the exponential curve would return in South Africa.

He said the country had therefore unfortunately only delayed the spread of the virus.

“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.

“Why is it so inevitable? We expect that when you get the virus, for the first three or four days, you will not transmit this virus. For the next four or five days you will be infectious. Then when you show symptoms you will be infectious for two weeks or so.

“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.

“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.”

Karim said that by being proactive community health workers could now 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 four stages of the response so far

The professor said the first stage was preparation, the second was primary intervention, the third was lockdown and the fourth would be ongoing monitoring and people observing social distancing and hygiene measures to prevent themselves or others becoming infected.

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The professor said this coming week would be critical to see what the community rate of infection was. By 18 April, 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 coming 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.

The next four stages of the response

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Stage 5 would be about finding where the virus was spreading and needed to be dealt with. Stage 6 had already started. “We need to be ready for when those patients come. We need to be ready with triage.

“When someone is sick, you go to a field hospital. A decision is made to send you to hospital, if you need to be ventilated. You hold the pressure off the main hospitals.”

He said that Stage 7 would be about dealing with the psychological and social impact of people dying.

Stage 8 would require ongoing vigilance and “keeping one step ahead of the virus”.

The professor said he was showing the public this so that it could have an idea of where the country was and where it’s going. He pointed out that it was important to fight the small flames before they became raging infernos. Community health workers would be the ones looking for the small outbreaks.

“It’s much more difficult to put out raging fires than small flames. We’re not sure we’re going to succeed but we’re going to try. We are not going to wait for patients to rock up at hospitals to react.”

There would be a surveillance programme to complement the community screening to act as a “canary in the coal mine”.

“We want to know where we are.”

Once a month or more often there would be a national surveillance day, and schools, mines, businesses and other institutions would be selected to gain a 5% sample using swabs or finger pricks to gain a picture of how far the virus may have spread.

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Karim discussed how Stage 6 was going to be complicated by the regular flu season, the millions of people with HIV and how to protect the elderly, particularly those more than 70 years old.

He said that poor access to healthcare had been identified as a major reason for why black people were dying in greater numbers in the US, which could not be allowed in South Africa.

Children would have to be kept away from the elderly, because they might infect them.

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Towards the end of the presentation, Prof Karim said the net effect of people wearing cloth masks, even if home-made, showed that it would prevent the spread of the virus. Clinical studies had shown that it prevented people with the virus from spreading it, though there was not enough evidence that it stopped people from contracting the virus.

He said washing of hands remained the most important, followed by social distancing and then masks.

“Have two masks. One you wash and let dry, and then another you can wear that day when you go out.”

Karim advised strongly against any member of the public using medical or surgical/N95 masks, since those would be needed for hospital staff on the front lines.

The BCG vaccine

Prof Karim said that the BCG vaccine was only meant to prevent severe forms of tuberculosis. A paper from researchers in New York had found that countries with a universal BCG vaccine policy were less affected by the coronavirus, but Karim said this was possibly a flawed study and that over time the world was likely to see that populations everywhere would probably be affected in a similar way. It was more likely that the countries were merely on a different trajectory. He had been told by experts in China that they had not noticed a difference between patients vaccinated with BCG and those who had not.

He said he would love nothing more than for the theory to be true, but he was sceptical.

Karim said climate would have little effect on the virus, but the fact that South Africa and Africa in general had far more youthful populations would most likely result in the continent having a far lower overall death rate.

You can watch the engagement below as it happened, courtesy of eNCA. 

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