A leading epidemiologist and respiratory infectious diseases expert, Professor Shabir Mahdi, has expressed deep concern that the fast-approaching COVID-19 peak in the Western Cape will overtake bed occupancy thresholds in the province’s major tertiary public hospitals. The anchor guest in a webinar hosted by Discovery Health in conjunction with the SA Medical Association in early June and attended by over 1 500 clinicians and other healthcare workers, Prof Mahdi said it was “frightening,” that the Western Cape’s main hospital ICU’s were already full of COVID-19 patients when the epidemic was not even at a third of its projected upward trajectory. The province is the country’s worst-affected, carrying over half of the estimated C-19 infection and mortality burden. Professor Mahdi said winter medical ward bed occupancy in State hospitals was usually 90% due to seasonal influenza. Citing Italy and Spain’s overwhelmed facilities, he said lower income countries had, ‘far lower bandwidth,” when it came to a confluence of the coronavirus peak and the usual winter influenza surge.
“We won’t be able to cope in spite of our valiant efforts to increase bed capacity. It takes an entire generation to rebuild a healthcare system. The lockdown enabled us to begin identifying symptomatic cases and begin testing and tracing – but we fell short, because this wasn’t in place at the start of the lockdown,” he warned.
Predicting that the epidemic would peak in the Western Cape at the end of July, he said the rest of the country would, on average, peak around a month later.
“The lockdown won’t eliminate the virus. Lockdown only works with aggressive testing of cases, tracing and isolation and/or quarantine. That has to happen very early on to prevent community transmission. That opportunity passed us by even before even the Level Five lockdown. With the first 20 imported cases, you need to trace up to 90% of all contacts – not just those in same household,” he stressed.
The hard truth on SA’s testing and tracing
He said South Africa’s claim to have a 90% tracing success rate almost certainly referred to only household contacts.
“I’m not talking about that. I’m talking about anyone who’s been in contact for 15-30 minutes, within a meter and a half radius. In high income countries they talk about one person having 20 contacts per day. We have, on average, as many at 70 contacts per day, research done in the Western Cape shows.”
Prof Mahdi said ideally, it took about three days from the time an individual showed symptoms to entering isolation. Calculating from the time of infection to signs of symptoms, to isolation, added up to six days. Assuming a conservative 20 contacts per person, that meant 120 contacts needing follow -up.
“So, when you’re diagnosing 100 new cases per day, that comes to 120 000 contacts to follow up. The research so far shows 70% of these need tracing before you can begin containing the virus. It’s just not feasible. The countries that succeeded, like South Korea and Singapore, used high-technology, (cell phone location), to trace contacts – and had already developed this plan from their MERS coronavirus outbreak in 2012,” he added.
He was at pains to dispel the myth that because of the urgency of the pandemic it was acute and would dissipate fairly quickly.
Prepare for a two-year pandemic
“Some naively believed the lockdown would contain the virus. We’re going to have waves of outbreaks for about two years. This is not a 100-metre sprint, but an ultra- marathon. With the 1918 “Spanish flu” pandemic, the second wave was actually more severe than the first, and they had four waves, up to 1920. That’s pretty much where we’re headed globally. We either develop herd immunity and it becomes a seasonal problem with some people. However, the only thing that will shorten the time period and render this a more of a nuisance virus will be a vaccine,” he warned.
It was ‘biologically implausible’ that the decrease in cases in the first week of SA’s lockdown had anything to do with lockdown. In truth, this represented people infected before lockdown.
“Our testing actually decreased during the first week of lockdown, compared to the week before. Over the five-week lockdown, the average number of cases per day was 30-40 in the first week, rising to close on 400 during the last week. That came with a ten-fold increase in testing,” he added.
Non-pharmaceutical’ intervention, (individual risk-reduction behaviour-change) was no guarantee against infection – it’s main value was to slow the spread rate of the virus; and this was now critically important, time-wise.
“We need a vaccine sooner than 60% of the population are infected. It’s at that point in time that we expect herd immunity to kick in. Now, whether natural infection actually induces sufficient immunity for herd immunity to kick in is a completely different story,” he stressed.
It was at this point in time that the (viral) reproduction rate dropped below one new case for every new person infected (by changing the percentage of the population susceptible to the virus).
SA’s case fatality risk compares well
He said the case fatality risk in South Africa for hospitals stood at 12% (compared to 2% in the general population) and this compared very favourably
to Italy and the United Kingdom, where the common denominator used was hospital case fatality.
Of every 1000 adults over a two to three-year period, about 25 would be hospitalised, with five dying. About 80% of those over 65 years old could die, he said, using multiple graphs and spread-sheets to illustrate.
Yet in South Africa, in contrast to many older populations in the northern hemisphere, there was a disproportionate number of people under the 65-year old threshold carrying high-risk co-morbidities, such as hypertension and diabetes, which changed the picture dramatically. Yet in the 18-45 age grouping, among those with no co-morbidities, none of the 1000 would die, while for children under 18 years old, it would be ‘unfortunate” if even one child was hospitalised, let alone died, he added.
Of Italy’s death-peak of 30 000 on May 5th this year, none were children, he emphasised.
“I’ve been doing respiratory viruses in South Africa for 25 years and this is the first one I’ve come across where I see kids being spared the severe effects of a virus,” he observed.
He said comparing statistics by country was a dangerous and inaccurate occupation.
The Centre for Disease Control (CDC) estimated that 1,3 million C-19 tests had been done in Africa, with just over half in South Africa. This pointed to an overall lack of capacity, with many countries relying on a single laboratory. (Lesotho relies on SA labs – for example). He cited the 2009 Swine flu pandemic which initially showed that the fewest number of confirmed global cases were from Africa. Yet then the final data were probed, more than 50% of all deaths were from Africa and South East Asia.
Prof Mahdi said South Africa had the capacity, but not the capability, and urged for testing to be focussed where risk priorities existed such as hospital patients and healthcare workers.
“We need testing results in 12-24 hours. Otherwise our healthcare workers will unknowingly be exposed and infect patients. Testing needs to be urgently goal-directed. Getting results up to seven days later makes testing a meaningless exercise, because people are far less infectious by then,” he stressed.
He said the NHLS had the capacity to get 36 000 tests done within 24 hours, but couldn’t do it because of a global shortage of testing kits.
Testing kit relief imminent
President Cyril Ramaphosa announced subsequent to Prof Mahdi’s webinar, that SA was sourcing the urgently-needed kits from 15 million being secured monthly from mid-June by the African Level Platform, while Health Minister Dr Zweli Mkhize’s lead advisor, Prof Salim Abdool Karim, said that after ‘disappointing’ initial test times, the NHLS was by June 20th, starting to trim backlogs down to a turn-around time of between 48 and 72 hours.
Quizzed by his audience on progress with a vaccine and general immunity after infection, Prof Mahdi said that while immunity was protective against severe disease and illness, a person could get re-infected. He warned against C-19 recovered healthcare staff believing they were ‘safe” once back at work.
The most promising and advanced candidate vaccine so far was under development in the United Kingdom. This chimpanzee adenovirus vaccine trial embraced 200 volunteers after the data on primate studies showed that a single dose induced neutralising antibodies that protected against severe disease when challenged with infection. However, the UK’s challenge was finding enough volunteers to increase their sample size (in a rapidly plummeted infection curve). The good news was that clinical trial approval in South Africa for the same candidate vaccine were imminent, enabling rich sample size pickings and hopefully showing initial results before Christmas.