RAZINA MUNSHI: Why SA’s Covid-19 ‘positivity rate’ is so high
From dropping restrictions on religious gatherings to allowing fully loaded taxis, the evidence suggests SA policymakers are not taking heed of the frightening data we’re getting every day
Social distancing, positivity rate, self-isolation, asymptomatic, co-morbidities, PPE – the Covid-19 glossary keeps expanding.
But it is still eclipsed by the volumes of data now at our disposal — daily infection and death rates, global trends, breakdowns by province, age, gender and testing statistics.
Admittedly, it is a lot for South Africans to take in. But it’s worth pausing to understand some of it.
Take the “positivity rate”, for example, which for SA has been an average of 26.6% for the past seven days. In a nutshell, this means that for every four Covid-19 tests conducted in this country, one person is positive.
So what does that reveal?
A positivity rate that is too high may mean a country is only testing its sickest patients, who seek medical attention, and isn’t casting a wide enough net to know how much of the virus is spreading within its communities, according to Johns Hopkins University.
On the flip side, a low positivity rate could mean a state has sufficient testing capacity for the size of its outbreak, and is testing enough of its population to make informed decisions.
Either way, this figure is a helpful tool to counter the spin hurled by US president Donald Trump, who has repeatedly suggested that the rising US infection rate is good news, because it points to improvements in testing.
As this article by health news website Stat shows, increased testing accounted for the rise in case numbers in just seven US states, between mid-May and mid-July. In the other 26 states — among the 33 that had case increases during that period — the case count rose because there was actually more disease.
This is where the positivity rate is illuminating. Two countries may have the same number of cases, but if one conducts double the amount of testing, its outbreak is likely much less serious than the other.
For example, Mexico’s total infection rate is only slightly lower than SA’s. Yet it conducts far fewer tests, and has one of the world’s worst positivity rates, at 62%. Coupled with an extremely high rate of excess deaths (deaths not reflected in official Covid-19 reports), this suggests the pandemic in Mexico is far worse than the data shows.
Unfortunately, SA’s rate of 26.6% is nothing to brag about. The country’s positivity rate is the ninth highest in the world. And while we may be testing more than Mexico, this suggests we aren’t doing enough — and that our epidemic is truly out of control.
Though decisions about opening up SA’s economy, frustratingly, don’t always appear to be based on science, figures such as these are an important tool to guide policy decisions.
The World Health Organisation (WHO) advised governments that, before reopening, positivity rates should be at 5% or lower for at least 14 days.
The Center for Public Integrity, a Washington-based nonprofit newsroom, recently published a document, which was prepared for the White House but not publicised, which suggested that more than a dozen states should switch to stringent protective measures: limiting social gatherings to 10 people or fewer, closing bars and gyms and asking residents to wear masks at all times.
One of the two data metrics it assessed to make this call was the positivity rate, the other being daily infection rates.
Mountains of data
The stories about this pandemic are best told from hospitals, factories, nursing homes and meatpacking plants. But the increasingly complex spread of numbers has provided fascinating insight, a point The New York Times unpacks this week.
It doesn’t take an expert to debate positivity rates any longer. And the same can be said about understanding hospitalisation numbers, trends in daily infection rates, fluctuations in testing, or the number of available ventilators.
At the same time, data-gathering operations by newspapers, universities and volunteers have sprung up in response to the pandemic, monitoring and collecting coronavirus metrics around the clock.
And, the NYT says, elected officials who were not particularly well versed in public health or infectious disease when 2020 began now sound a little like epidemiologists as they spend their days knee-deep in data and making policy decisions based on the figures before them.
SA’s scenario seems wholly different. From dropping restrictions on religious gatherings to allowing fully loaded taxis, the evidence suggests policymakers are simply not taking heed of the frightening data we’re now getting every day.
* Munshi is News & Fox editor of the FM
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