Covid-19

ANALYSIS

Unravelling the riddle of the Western Cape’s high Covid-19 numbers

The Western Cape government has repeatedly pointed out that the province has been undertaking strategic testing at a scale that no other province has come close to matching. (Photos: Gallo Images / Misha Jordaan | Sharon Seretlo / Gallo Images via Getty Images | EPA-EFE / Kim Ludbrook)

Ask why the Western Cape is currently recording over half of all the Covid-19 deaths in SA, and you’ll be told it’s because the province has more than half of all confirmed Covid-19 cases in the country. Ask why the province has so many Covid-19 cases, and the main reason you’ll be given is because of the scale and the nature of its testing. But puzzling questions remain.

On the face of it, the Western Cape’s Covid-19 figures are a jarring anomaly compared to those from the rest of the country’s provinces.

As of 20 May, the Western Cape accounts for 11,262 of the country’s total 18,003 confirmed Covid-19 cases, just over 62%.

In the previous 24 hours before provincial officials held a press conference on Wednesday, the Western Cape had recorded 39 Covid-19 deaths.

The cumulative Western Cape Covid-19 death toll is now at 211, while the other eight provinces have together contributed 128 deaths to the national total.

“Now you can start to see the numbers rising,” Western Cape Premier Alan Winde told Wednesday’s media briefing – but the alarming climb of the province’s figures has been evident for weeks.

On social media, the Western Cape’s grim tally has seen it painted as the country’s Covid-19 black sheep, with its residents accused of bringing the situation upon themselves by not adhering to pandemic mitigation efforts.

In response, the Western Cape government has repeatedly pointed out that the province has been undertaking strategic testing at a scale that no other province has come close to matching.

The records bear this out. Between 20 April and 10 May, for instance, the testing report compiled by the National Institute for Communicable Diseases (NICD) shows that the Western Cape accounted for almost a quarter of all lab tests conducted nationally: 51,248 tests out of a total 222,209.

It is not just the volume of testing the province is undertaking that is significant, but also the kind of testing.

Provincial health spokesperson Mark van der Heever told Daily Maverick: “Our screening and testing teams are deployed based on data which actively identifies and follows the ‘bush fires’ – the pockets of infections within communities.”

In other words, the province is proactively testing people in areas which have already been identified as likely coronavirus hotspots, so the tests are likely to come back positive.

The Western Cape’s current Covid-19 fatality rate is only in the same ballpark as the other provinces’ if we assume that the other provinces’ testing numbers are correct.

This too is reflected in the NICD data. Between 4 and 10 May, for instance, 1% of tests in Gauteng came back positive, whereas 12.1% of tests in the Western Cape came back positive.

In summary, Western Cape authorities have repeatedly contended that although the province’s figures look much more alarming than the rest of the country’s, this is a misperception which fails to account for the scale of highly targeted testing in the province. Or, to put it another way: We have more Covid-19 cases because we’re better at finding Covid-19 cases.

Professor Landon Myer, head of the school of public health at UCT, largely supports this analysis.

“The Western Cape is identifying more cases than the rest of South Africa per 1,000 [ratio of the] population, certainly, but that is most likely due to the highly functional provincial Department of Health relative to other parts of the country,” Myer told Daily Maverick over email this week.

“There is a targeted testing programme that has extensive human and financial resources, close monitoring and oversight, state-of-the-art information synthesis and reporting systems, etc, etc.”

Myer also pointed out that although the Western Cape’s death numbers look vastly higher than the rest of the country’s, they are relatively similar when you do the maths of death per case identified.

As of 20 May, the Western Cape’s Covid-19 case fatality rate was around 1.9% (211 deaths from 11,072 total cases).

The province with the second-highest number of confirmed Covid-19 cases, Gauteng, had a slightly lower fatality rate as of 20 May: 1.1% (27 fatalities from 2,400 total cases).

Yet, if the Western Cape’s Covid-19 case numbers are the highest purely because the province is doing the best and most testing, the presumption is that if other provinces were to follow suit, their numbers would rise equivalently. In other words, there must then be thousands of Covid-19 cases currently going undiagnosed in other provinces.

But if that were the case, one might expect to see a corresponding rise in the number of deaths in other provinces. The Western Cape’s current Covid-19 fatality rate is only in the same ballpark as the other provinces’ if we assume that the other provinces’ testing numbers are correct.

If Gauteng’s real Covid-19 case numbers are actually 10 times higher – 24,000 – then if the current fatality rate of 1.1% is consistent, the province should have recorded around 264 deaths so far, rather than 27.

Cases of Covid-19 might slip through the cracks, but it is harder for a dead body to do so – even though there are already reports of delays in conducting autopsies and issuing death certificates in some areas.

Professor Tom Moultrie, the director of the centre for actuarial research at UCT, told Daily Maverick that “near real-time death monitoring” is taking place in order to ensure that sudden spikes in unexplained deaths are not missed, precisely because it is a known possibility that someone may die of Covid-19 without having been diagnosed in life.

“The deaths are a mystery,” Moultrie said.

At the Wednesday briefing, Cloete also warned that even the Western Cape’s current testing rate will be unable to keep pace with projected new cases in the weeks ahead. “We will not be keeping up with detecting all the new cases as we grow,” Cloete said, adding that lab testing capacity was already “under severe strain”.

It is important to pause and note that the relationship between incidence rates and death rates when it comes to Covid-19 has been puzzling in many parts of the world. Germany has so far reported 96 deaths per million inhabitants, compared to 520 per million in the UK.

Business Maverick editor Tim Cohen quotes British economist Robert Skidelsky on the difficulty of predicting health outcomes: “Too many variables – including, say, medical capacity or cultural characteristics – scrambles the model, and it starts spewing out scenarios and predictions like a demented robot.”

That noted, the riddle of the Western Cape figures – if indeed it is a riddle, as many deny – has a number of possible explanations.

Option 1: There is no difference between the picture of the pandemic in the Western Cape and the other eight South African provinces, except when it comes to testing. In this scenario, if the other provinces were to immediately adopt the Western Cape’s testing approach, their case numbers would immediately sky-rocket. This would suggest that hundreds of Covid-19 deaths in other provinces have gone unrecorded thus far, though there is little indication that this is the case.

Option 2: Even though people are going undiagnosed in other provinces, they are also not dying at a commensurate rate. This would suggest that there is something about either the demographic features of the Western Cape population that make residents more vulnerable to a severe disease course, or that there are social determinants at play – such as the conditions in which they live, or their failure to adhere to lockdown.

When Daily Maverick asked Moultrie if there were existing demographic features of the Western Cape which would suggest greater susceptibility to coronavirus infection, such as an older population, he replied: “Not that I can think of.”

UCT professor of public health Leslie London pointed out to Daily Maverick that at other points in South Africa’s health history, certain provinces have had unique experiences with certain diseases which are hard to explain.

“There was always a notion that the Western Cape was unusual for having higher rates of TB. People thought it was the damp, the high rates of alcohol abuse, etc. Nobody could work it out. Then HIV arrived and every province had high rates of TB. We never found a reason for the TB exceptionalism. I am not sure if something is operating here in the same way for Covid-19,” London said.

Option 3: It is true that the Western Cape is doing more targeted testing, but it is also likely, assuming the accuracy of death records in other provinces, that the Western Cape also simply has more cases at the moment. Whether or not the other provinces “catch up” remains to be seen.

This is the position towards which Western Cape authorities seem to be shifting.

Questioned by Daily Maverick on the issue at Wednesday’s press briefing, provincial head of health Dr Keith Cloete said:

“I think it’s very clear today that community transmission has been established earlier in the Western Cape… Other provinces didn’t have community transmission at the same point.”

The theory now is that the Western Cape’s coronavirus infections were “seeded”, to use the public health term, ahead of other South African provinces in March: likely due to higher tourist numbers in the Western Cape. (Some have also speculated that the Cape Town Cycle Tour, which drew around 35,000 people together on 8 March, may have played a role – though Professor Myer warns that such theories are not “more than conjecture”.)

Cloete said it was possible other provinces might “get to the point” where the Western Cape is currently.

“When their cases increase, their deaths will increase,” Cloete said.

At the Wednesday briefing, Cloete also warned that even the Western Cape’s current testing rate will be unable to keep pace with projected new cases in the weeks ahead. “We will not be keeping up with detecting all the new cases as we grow,” Cloete said, adding that lab testing capacity was already “under severe strain”.

He warned, too, that the province’s quarantine capacity “will ultimately be exceeded”.

But the acknowledgement that the Western Cape’s Covid-19 situation may currently be uniquely severe has not been accompanied by an acceptance that a higher level of lockdown in the province should be maintained.

Premier Alan Winde on Wednesday called for the province to move as soon as possible to Level 3 lockdown in combination with the implementation of targeted hotspot plans.

Winde argued that no more jobs could afford to be lost in the Western Cape as a result of the lockdown.

“Even if we lift restrictions now, over 200,000 jobs are going to be lost in the Western Cape alone,” Winde said.

Whatever happens in the Western Cape cannot help but affect the rest of the country. Political analyst Professor Stephen Friedman wrote in a Facebook post this week:

“The demand by business that we move to Level 2 for the whole country is seriously irresponsible until Western Cape has the virus under control. Level 2 means that travel between provinces is allowed which would, of course, make it likely that the Western Cape’s problem would become everyone’s.” DM

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