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Infectious Diseases

Updated 29 April 2020

Covid-19: Is SA’s testing criteria too restrictive?

There are some healthcare workers who feel South Africa’s COVID-19 testing criteria should be broadened. Amy Green asked some local health experts for their views.

Who should be eligible for Covid-19 testing in South Africa? The answer is different depending on who you ask. While the current eligibility criteria for testing is clear, there are some working in the field who feel these criteria are too restrictive and should be broadened.

Testing is central to the Covid-19 strategy in South Africa and in many other countries. Once a person tests positive, they can isolate, and the risk of further onward transmission from that person can be reduced. Apart from this benefit for the community, earlier testing also makes it more likely that individuals with Covid-19 will receive the healthcare services they need in time should they become seriously ill.

The current criteria according to a National Institute of Communicable Diseases (NICD) brief, dated 9 April 2020, the criteria for persons under investigation (PUI), i.e. those who should be tested for Covid-19, are: Persons with acute respiratory illness with sudden onset of at least one of the following: cough, sore throat, shortness of breath or fever [> 38 degrees Celsius (measured) or history of fever (subjective), irrespective of admission status]. 

According to Professor Adrian Puren from the NICD the “case definitions used by the NICD are informed by consultation with South African or international experts in the field and guidance from reputable organisations such as the World Health Organisation. The final definitions are reviewed by the Ministerial Advisory Committee and signed off by the National Department of Health. In the case of community screening, the current criteria are (having) two respiratory symptoms,” he says. 

But is there merit in broadening these criteria, for example, for anyone displaying even one symptom or for all persons admitted to hospital regardless of respiratory illness status? “The NICD has revised its criteria for testing as the epidemic has evolved,” says Puren. “The NICD took pragmatic decisions based on the knowledge available at the time as well as the availability of resources (both human and testing reagents/platforms). The case definition is a guide and the doctor and patient will always review risk and make a decision on whether to test or not on an individual case by case basis.”

Broader criteria where possible

Dr Tom Boyles, an infectious diseases specialist based at Helen Joseph hospital in Johannesburg, says there is merit in broadening the criteria. In fact, he and his team, who are assessing the readiness of a number of clinics in the city to combat Covid-19, are testing anyone displaying even just one of the four symptoms. “I’m not suggesting everyone is doing that or should be doing that - not on the ground, in other words in communities, at least,” he says. 

According to Boyles a “ballpark figure” of 5 000 people per day walk into the city’s clinics displaying at least one of the Covid-19 symptoms. “If we put testing in every clinic, we could test about 5 000 people per day just in Johannesburg. But to do that we would need to set up the capacity, provide the consumables and, crucially, ensure we have the ability to follow those people who test positive up properly,” he says.

According to figures provided by Health Minister Dr Zweli Mkhize last Thursday, just under 10 000 Covid-19 tests were conducted in the entire country in the preceding 24 hours. For the three days after that between 7 500 and 8 900 tests were conducted. For most of last week national numbers fluctuated between 5 000 and 7 000 tests a day. (Spotlight previously reported on South Africa’s testing scale-up here and here.)

Boyles said the testing strategy should prioritise certain groups, but the health system is patchy with regard to following through on this. For example, health workers, whether symptomatic or not, should be regularly tested. There have been directives issued to health facilities to this effect. This is important because health workers come into regular contact with vulnerable patients, for example those with pre-existing chronic conditions and weakened immune systems. “The next group of people are sick people – anyone who comes into a hospital with a respiratory condition. These people should be held in wards away from Covid-19 negative patients until the outcome of the test is known. If they are found to be negative, then they can be moved into wards with other negative patients,” says Boyles. 

Why are we not scaling up more quickly?

The National Health Laboratory Service (NHLS) previously told Spotlight it has the capacity to do 15 000 tests per day. It set a target of 36 000 tests per day by the end of April. While there has been a clear upward trend in recent days, daily numbers are still below 10 000 and often still close to 5 000. Why then is the country testing at lower rates than envisaged? Is it a capacity issue or is it down to the eligibility criteria? 

Professor Shabir Madhi, director of the South African Medical Research Council’s Respiratory and Meningeal Pathogens Research Unit, says it is both. “It’s both due to the number of people meeting the eligibility criteria and a number of other reasons. For example, the roll out of community testing only started very recently, just before the Easter break, and we haven’t been able to ramp it up to full scale. There are a number of bottlenecks, such as staff training, which is ongoing as well as the materials that are required for testing being in short supply.

The one constraint is that swabs and material needed for testing in the laboratory are in short supply,” he told Spotlight. According to Madhi, community testing should have been started long ago. “We should have been doing that right at the start of the lockdown. ”But, should we be testing every person who is admitted into hospital instead of only those with respiratory illnesses? “We could make a case for testing everyone in hospital settings.

In the United States, one study done on women coming into hospital to give birth showed that about 15% of them were infected and 80% of these were asymptomatic,” says Madhi. However, he says that the risk with this would be that resources to test symptomatic individuals in the community could be diverted to asymptomatic patients in hospital. Boyles also “sees merit” in testing all hospitalised individuals. “It would be like testing asymptomatic health workers. I see the benefit because Covid-19 can spread easily in these settings where physical distancing can’t be practiced and, like staff, patients can come into contact with other vulnerable patients,” he says. 

Questions over capacity

Puren points out that testing and tracing places high demands on the health care system and laboratories. “There is certainly capacity in the case of the laboratory to perform testing but to meet the expected targets requires an increase in staff numbers. An additional consideration is the availability of reagents given the current high levels of testing elsewhere in the world,” he says. 

University of KwaZulu-Natal’s Professor Andy Gray sums up the situation. “The obvious con to testing more widely is the impact on the laboratories, which could be overwhelmed, consuming resources and delaying results for positive cases. Delayed results mean more PUI under isolation, which could also overwhelm that capacity. The pros to more liberal testing, if resources and capacity allow, is that milder cases may be diagnosed, interrupting transmission, and a better idea of true incidence obtained,” says Gray. 

“As capacity to conduct molecular tests expands, I do think that we need to widen the definition of PUI, but carefully,” says Gray. “The travel history is becoming less important, and if asymptomatic spread is happening, so is close contact with a known case. The last criterion can be expanded to include those with less severe symptoms. However, that needs to be done in a careful, stepwise fashion, so as not to overwhelm the testing capacity. There could also be a place for repeated testing of those at high risk of exposure, notably healthcare workers, even if they are not symptomatic.”

Testing is the key to isolation

According to Boyles, the “key to mass testing is not simply the testing itself, it’s the ability to isolate people who are found to be positive”. “Self-isolation is all very well for people in Sandton with a spare room with an en-suite jacuzzi and Wi-Fi, but the majority of South Africans live in crowded living conditions where a call to isolate is futile,” says Boyles. “What’s the point knowing someone is positive when there is nothing we can do about it?”

Boyles is advocating for the setting up of isolation facilities using, for example, large sports stadiums, where infected individuals can stay for the required 14 days until they are no longer infectious and then return home. “We can learn from the Chinese in this regard because this is something that they did very well,” he says. “In this setting there is the advantage that everyone there is positive, except for the staff, and can’t spread Covid-19 to people who are negative, as well as the advantage that health workers can easily monitor people’s symptoms and if an individual deteriorates, they can be rapidly sent to hospital.” 

He says it is unfortunate that this kind of set-up has very negative associations with how drug-resistant tuberculosis (TB) patients were treated in the past – being sent to hospitals far away from their families for protracted periods of time by force.  “The terrible precedent of trying to lock away TB patients for six months is counterproductive. But in this case people aren’t likely to die, it would be for a short period of time, and they should be allowed to bring their babies along. We would need to make those places attractive to people and try [to]make them understand it’s their duty to isolate there without forcing them,” he says. 

Flattening the curve

How does South Africa fare when compared to what is being done in other countries when it comes to testing? “In Italy they are mainly testing people with severe disease in hospitals because that is where their epidemic demands its focus. In Germany they are testing up to 50 000 people each day who are symptomatic. In the United Kingdom they are testing less than 10 000 each day but the focus is on severe illness,” says Madhi.

However, Madhi says it is not constructive to compare South Africa’s testing approach to that of other countries as the epidemic and socio-economic circumstances here are entirely different. He believes that the current testing criteria are adequate for what the country is trying to achieve – to “flatten the curve”.

“Many people are using this phrase, but I don’t think the majority of the public understands it. Flattening the curve doesn’t mean we are trying to end the epidemic. Successful elimination of Covid-19 in South Africa is not on the cards. What we are trying to do is to control the rate of infection. Flattening the curve does not mean fewer cases, it will be the same amount of cases but taking place over a broader period of time. We need the cases to be more spread out so that the health system can manage with the additional load,” he explains.  

*This article was produced by Spotlight – health journalism in the public interest. Like what you’re reading? Sign up for our newsletter and stay informed.

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