The world is changing fast and to keep up you need local knowledge with global context.
South Africa has been leading the way in keeping a lid on Covid-19 contamination, with far fewer cases and deaths reported than expected at this stage of the pandemic. The government has shared the thinking on why South Africa has bucked the trend and also the future scenarios that are being factored into decision-making at the highest levels. Minister of Health Zweli Mkhize has made available the full details of a presentation by Professor Salim Abdool Karim, the chair of the Ministerial Advisory Group, on the trends and next steps in combatting Covid-19 in South Africa. Karim has impressive credentials and has high-standing in the international global health and academic community. Conspicuously absent in the presentation slides is any mention of the BCG vaccine, which some scientists have suggested may be shielding many from the virus as it has been compulsory in SA for many decades. The details of the presentation provide much food-for-thought as South Africans stay at home under stricter lockdown measures than have been implemented elsewhere – and point to the way forward. – Jackie Cameron
South Africa’s Covid-19 epidemic: Trends & next steps – key takeaways
- Covid-19 cases have declined in the last 2 weeks while NHLS test numbers increased ie. while testing in people and communities without medical aid increased Note: Overall testing is still below the target of 10-15,000/day;
- Can SA escape the worst of this epidemic? Is exponential spread avoidable? No! Not unless SA has a special protective factor (mojo) not present anywhere else in the world;
- Our population will be at high risk again after the lockdown;
- Infectiousness period includes 4-7 days before symptoms ie. people can spread it without knowing;
- The virus spreads too fast normally;
- Government interventions have slowed viral spread, the curve has been impacted and we have gained some time;
- Time to flatten the curve even more;
- South Africa has a unique component to its response, ie. active case finding;
- Only South Africa has >28,000 community health care workers going house-to-house in vulnerable community for screening & testing to find cases;
- New quicker and simpler diagnostics becoming available;
- New treatments become available; and
- Time to prepare for the medical care needs.
Current stages of SA’s response
Stage 1: has entailed: Preparation • Community education • Establishing lab capacity • Surveillance
Stage 2: Primary prevention • Social distancing & hand-washing • Closing schools and reduced gathering • Close the borders to international travel
Stage 3: Lockdown • Intensifying curtailment of human interaction
Stage 4: Surveillance & active case-finding • The Community response: door-to-door screening, testing, isolation and contact tracing
Community transmission levels to guide next steps & the lockdown
• By 18th April, will know if community transmission interpretation accurate (~67 cases/day; CI: 45 – 89)
Epidemiological (Ro ) criterion for lockdown – if average daily cases (- active screening) from 10 – 16 April is: • 90+, then continue lockdown • 45 – 89 AND CHW rate is >0.1% then continue lockdown • 45 – 89 AND CHW rate is <0.1% then ease lockdown • < 44, then ease lockdown
- Expect large daily variations & some increases in +ve tests due to active case-finding (passive vs active cases)
- Abrupt return may increase spread – plan the systematic easing of the lockdown over several days
- Stepwise approach to reduce risk of rapid transmission taking economic imperatives & social disruption into consideration
Next stages of South Africa’s response:
Stage 5: Hotspots • Surveillance to identify & intervene in hotspots • Spatial monitoring of new cases • Outbreak investigation & intervention teams
Stage 6: Medical Care (for the peak) • Surveillance on case load & capacity • Managing staff exposures and infections • Building field hospitals for triage • Expand ICU bed and ventilator numbers
Stage 7: Bereavement & the Aftermath • Expanding burial capacity • Regulations on funerals • Managing psychological and social impact
Stage 8: Ongoing Vigilance • Monitoring Ab levels • Administer vaccines, if available • Ongoing surveillance for new cases
Professor Karim’s roles include: Director: CAPRISA – Centre for the AIDS Program of Research in South Africa; CAPRISA Professor in Global Health: Columbia University; Adjunct Professor of Immunology and Infectious Diseases: Harvard University; Adjunct Professor of Medicine: Cornell University; Pro Vice-Chancellor (Research) and University of KwaZulu-Natal; Director: DSI-NRF Centre of Excellence in HIV Prevention.
Some audio and transcript excerpts taken from Professor Salim Abdool Karim:
Why is South Africa not on the expected Covid-19 epidemic trajectory?
I’ve chosen to compare South Africa with the UK, because for the first two weeks or so, the number of new cases we had in South Africa, was the same as the number of cases that we saw in the UK. In the initial period, the new cases in each of our countries at that point – after we reached 100 cases – was very similar.
On March 26, our line chooses not to continue the same upward trajectory that you see in the UK. That’s not to say that our two countries are compatible but certainly the initial trajectory of these two epidemics or similar. On March 26, the numbers declined and became stable, and the line flattens out. That’s the difference between the two trajectories that you see.
Is that unique to the UK?
Let’s compare the South African line. There’s a little line that looks like a sort of a knuckle where it goes up sharply and then takes a turn and then it flattens out. If you look at that line and compare it to a range of different countries, I’ve chosen here to compare it against the US, UK, Italy and China. It gives you some sense that every one of these countries when they get into that upward incline where we see that exponential line it simply keeps going. Not a single country that we have seen has this kind of turn. I’ve also compared our epidemic curve to some of the most successful countries that have been able to make quite a marked impact on the growth of the epidemic and those in particular, South Korea, Japan and Singapore. When you compare our epidemic, you can see that Singapore was able to make an early impact and to create a much steadier growth in their epidemic. Whereas if you look at South Africa, there’s been no other countries. Our epidemic trajectory is unique. No other country has reached that point and has been able to reach a stage where you get that plateau.
Why is South Africa different? Why is it that our new cases declined and have reached a plateau?
There are three possible reasons: The first, isn’t that we are just testing less? Is it that we’re just not doing enough tests, and that’s why we’re just seeing fewer cases? Is it that we actually are still doing a lot of tests, but we’re doing that in the private sector and not in the public sector?
We’re not getting a sense of what the epidemic is doing in our poorer communities that don’t have medical aid. The third possible explanation, is this reduction genuine? What’s the likelihood that it’s genuine and that it’s due to the interventions that we have implemented?
What do you see in that?
Over the two weeks, the South African epidemic went to a plateau phase. We see a continual increase in the number of tests that are being undertaken. We didn’t do much fewer tests. The overall numbers of tests have steadily increased in the last two weeks. It reduces a problem of lack of testing. Lack of testing may be a contributor. It’s certainly not a dominant one.
Are we not testing the poorer communities?
We look on the right-hand side, that’s the daily number of tests that are being done by the (NHLs). All of our poorer communities without medical aid will be coming to the NHL less for their testing. What do you see just at the time that you saw the plateau in the South African trajectory is the point at which the NHLs sharply increased the number of tests that it’s doing?
We’ve seen a steady increase in the number of tests in the NHLs. It’s not because we’re not testing in the townships in the communities. It has to be a third explanation. It’s unlikely due to a lack of testing. It’s unlike a decline in testing. It’s unlikely to due to the fact that we’re not testing in the communities the poorer communities. It most likely is due to some genuine effect. It’s not something we can say definitively but we can say that that’s the likely situation. Covid-19 cases have declined over the two weeks, while the NHLs numbers have increased. While testing in people in communities without medical aid has increased. We still need to do more in terms of testing. But, what we have seen is an increase.
This coming week is critical. We need to know what the average number of cases is going to be. We want to know what the community transmission levels are, because we want to use that to guide us on what next steps we should follow and how we should manage the lockdown.
On April 18, we will know if community transmission – whether community transmission has been kept low – is accurate. If we look at the 67 cases per day on average, the 95% confidence interval is 45 to 89. The true number of cases is between 45 and 89. We are 95% confident that the and then the number of cases per day, even though we are seeing 67 there’s some variability and that variability lies between 45 and 89. Using that as an objective criterion, based on how many people is an infected person is spreading it to. If we base it on that, then we have a set of criteria.
If the average number of daily cases – we have to exclude active screening – because that’s not comparing apples and apples. If we look at just the passive cases, between April 10 – April 16, and if we see 90 or more cases on average – between April 10 – April 16 – we need to continue the lockdown.
And the reason?
The average number of cases per day is going up. The R node is going above 1. We don’t want that. We want to keep R node at one or lower if we see a number of cases between 45 and 89 then we are in the same region as 67, within the margin of error. We want to use our community preference.
What is the active case finding telling us?
If that active case – has a screening positivity ratio that is, above one in a 1000 – we continue the lockdown. If it’s below 1 in a 1000 then we can ease the lockdown. Similarly, if the number of cases is 44 or lower, we can ease the lockdown because it tells us R node is less than 1. Using epidemiological criteria, we create a set of a clear approach as to how to deal with the lockdown. You must expect that there’ll be large daily variations because of the timing of the lab tests.
You have to look at it over a period of time. That’s why we look at a whole week at a time, and we compare weeks with weeks. If we end the lockdown abruptly, we may run the risk of undoing all of the effort and the benefits we have achieved. We’ll be putting high risk and lower risk people together, traveling in the same buses, taxis, and trains. We have to do something about it. We have to avoid that situation.
We need to think and plan for a systematic ease of the lockdown starting with transport hubs and then working our way down from the lowest risk to the highest risk.
We would hope that the number of new cases will steadily decline and disappear. That’s the end of the story. That’s very unlikely. We’ve managed to stem community transmission.
Once we end the lockdown – we’re going to have to end it at some point once – we end it because about 55m people are vulnerable to this virus. This is a completely new virus. No one in the world has encountered this virus before. We have no immunity. We have no vaccine. We have no treatment. We are all at risk. It doesn’t matter whether you’re white, black, young and old. You’re at risk because you have no protective immunity and that’s why as soon as the opportunity arises for this virus to spread we are likely to see the exponential curve again.
People have looked at other epidemics. Colleagues in India have modelled the Indian epidemic and they are currently in a 21-day lockdown. They show that when the epidemic is starting to go up, you instituted a lockdown, at the end of the lockdown the epidemic is likely to come back. Then you can look at Wuhan, where the institution of a long lockdown died something like 50 – 60 days of lockdown, and they then waited for no local transmissions for seven days before they lifted the lockdown. Are we going to see another small epidemic in Wuhan. As soon as travellers start coming into Wuhan reintroducing the virus to what extent the community doesn’t have immunity and we’re likely to see new epidemics?
As much as we have succeeded in stemming the flow of this virus in our communities and keeping community transmission at a reasonably low level – that is a success that no one else has achieved. Can South Africa escape the worst of this epidemic? Is the exponential spread avoidable. We cannot escape this epidemic.
Not unless South Africa has some special protective module that can protect us. Our population is at high risk because all of us have no immunity against this virus. We’ve never encountered it before. As soon as we end the lockdown, we will have that high risk.
Why is it that it’s so inevitable?
There are several reasons. When you acquire the virus – let’s say you get infected with the virus to date – we expect that for the first three or so days, in the incubation period you will not transmit this virus, but after, 5 to 10 days. You are now infectious. You are infectious before you have symptoms. You don’t even know you have this virus and you are in a position to transmit it.
How do you fight something that you don’t even know you have?
Once you show symptoms, you are also infectious. You are infectious for another two weeks or so. You have this long period of infectiousness, during which you spread around it and we know that normally when people are interacting with each other this virus can spread fast. On average, an infected person will infect about two to three other people.
If 10,000 people have the virus today, within three, four, five days that 10000 people will become 30,000 and then again another 4 or 5 days. You’re now at 90,000 because each person is infecting two to three others. This epidemic within weeks can grow very rapidly.
What we have seen is a slight difference in our curve and the government interventions have slowed the viral spread. The curve has been impacted. We have now gained time. Why is the delay important? Why is it that we should delay this viral epidemic? If we allow it to grow unchecked, we will see what you see in New York. You will see thousands of people trying to get into a hospital for care. We do not have enough ICU beds or ventilators or medical care. We cannot provide care to so many people at one time. We have time to flatten the curve. South Africa has a unique component to its response. It’s quite important that when you talk about how you tackle this virus every other country has simply had to wait. They saw these cases coming into the hospital and that’s how they recognise they had an epidemic.
In South Africa, we’ve chosen to go a different route. We’ve chosen to be proactive. We’ve chosen to go out there and do active case finding. We’re not going to wait till they come to the hospital sick. We’re going to go into the community. We’re going to find them before we get to a hospital. Only South Africa has done that because every other country before they knew it the epidemic was on top of them. We have over 28,000 community health care workers, going house to house in our most vulnerable communities, screening them and referring them for testing so that we can find the new cases.
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