Only herd immunity can control Covid-19 in SA – James Myburgh. MUST READ!

James Myburgh, the founder and editor of Politicsweb, has an extraordinary capacity to analyse big problems and shed light on the solutions. In this masterful piece, Myburgh – who has a PhD from Oxford – has applied his mind to the Covid-19 epidemic, in particular government plans to bring it under control. Myburgh undertakes in-depth number crunching and sizes up evidence gleaned from other countries that are in the mist of coronavirus panic. He concludes that a national shutdown will not prevent the inevitable. Covid-19 will spread far and wide, helped by HIV-Aids, TB and social and irresponsible younger South Africans. Ultimately, herd immunity will bring this under control, concludes Myburgh. His article is republished on BizNews, with permission. – Jackie Cameron

The coming winter flood

By James Myburgh

South Africa is in the initial phases of a Covid-19 epidemic, the disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This novel coronavirus, which emerged in Wuhan China in late 2019 is closely related to SARS-CoV-1, the disease that resulted in 8 098 cases, and claimed 774 lives in China, Taiwan and Hong Kong in the 2002 to 2003 period. As a new, highly infectious virus, humans lack immunity to it, and the production of a safe and efficacious vaccine is estimated to still be some 18 months away.

The first case in South Africa recorded by the National Institute for Communicable Diseases (NICD) was of a 38 year old man who had travelled to Italy, along with his wife and nine other people. Since then the numbers have rapidly stacked up as travellers returning from overseas have been tested. As of Thursday, 18th March, the NICD had conducted 3026 tests, of which 116 had returned positive results. 102 of these were people who had been overseas, and 14 were cases of local transmission. Many of these were, presumably, close contacts of the returning travellers. Anban Pillay, the Director General of the Health Department, told the Daily Maverick that none of these people had to place any patient who tested positive in intensive, or critical care.

These figures tell you about the epidemic that is currently raging in Europe, but little about what is actually going on in South Africa. The great question is to what degree community spread is already occurring under the radar of the NICD surveillance system, and for how long. Testing has been generally been limited to those who presented with symptoms (which are similar to the flu) AND who had recently travelled to high risk areas, or who had been in contact with known cases (also in health care setting), or who presented with “severe pneumonia of unknown aetiology”.

It is only the last that is likely to detect community spread in the early phases of the epidemic, and it is a lagging indicator as the great majority of people, and especially the youth, only develop mild flu-like symptoms (if any). In other words, it is possible for the virus to infect hundreds of people before the first severe pneumonia case is reported. In Northern Italy, or Washington State in the US, it was only when the elderly started dying in numbers that those regions realised that they had an epidemic on their hands.

It is likely that people infected with the SARS-CoV-2 virus have been coming into South Africa from Europe since early February (if not China before that) and initiating trains of local transmission in a number of different areas. In Australia, over 80 000 tests have been conducted and as of 19th March 2020 and 565 cases confirmed. Of these 259, or under half, were considered to be overseas acquired.

The real signal to look out for then is not the number of people returning from overseas with Covid-19, and their close contacts, but the first cases of acute pneumonia caused by SARS-CoV-2 in old age homes or informal settlement areas like Diepsloot and in Khayelitsha. The spread, and the severity of symptoms, may have been suppressed by the warm summer weather in the southern hemisphere. Last year the influenza season began in late April in South Africa, so any respite still being provided by our converse seasonality to the northern hemisphere will be potentially short lived.

To understand the likely course of the Covid-19 epidemic over the next six months it is useful to examine how it has affected societies elsewhere, and then compare them to our own.Unlike in Europe and the United States, China and South Korea currently have their epidemics largely under control partly through aggressive testing and contact tracing. This means that they have a fairly comprehensive picture of who has been infected by SARS-CoV-2, including those who displayed only mild symptoms. As can be seen from Tables 1 and 2 while the young can be infected, and be carriers of the virus, those under thirty were highly unlikely to die from the disease. While those under 50 accounted for 58,6% of all confirmed cases in South Korea, there have been only two deaths among under-50s so far. As you get older the fatality rate becomes higher, increasing dramatically for those over sixty.Table 1: Confirmed cases and deaths in South Korea as of 17 March 2020

Age-groupConfirmed cases% of all casesDeaths% of all deathsFatality rate
0 to 9

86

1,0%

0

0,0%

0,0%

10 to 19

436

5,2%

0

0,0%

0,0%

20 to 29

2 330

28,0%

0

0,0%

0,0%

30 to 39

856

10,3%

1

1,2%

0,1%

40 to 49

1 164

14,0%

1

1,2%

0,1%

50 to 59

1 602

19,3%

6

7,4%

0,4%

60 to 69

1 033

12,4%

16

19,8%

1,5%

70 to 79

539

6,5%

29

35,8%

5,4%

80+

274

3,3%

28

34,6%

10,2%

8 320

100,0%

81

100,0%

***

Table 2: Confirmed cases and deaths in China between 1st January and 11th February 2020:

Age-group (years)Confirmed cases% of all casesDeaths% of all deathsFatality rate
0 to 9

416

0,9%

0

0,0%

0,0%

10 to 19

549

1,2%

1

0,1%

0,2%

20 to 29

3 619

8,1%

7

0,7%

0,2%

30 to 39

7 600

17,0%

18

1,8%

0,2%

40 to 49

8 571

19,2%

38

3,7%

0,4%

50 to 59

10 008

22,4%

130

12,7%

1,3%

60 to 69

8 583

19,2%

309

30,2%

3,6%

70 to 79

3 918

8,8%

312

30,5%

8,0%

80+

1 408

3,2%

208

20,3%

14,8%

44 672

100,0%

1023

100,0%

2,3%

Source: Verity, et al.

Both countries had the resources and state capacity to prevent the epidemic spinning out of control, and to provide reasonable care to those suffering from severe symptoms. In Wuhan 6% of confirmed cases had severe illness, in the form of pneumonia. Here there is obviously a huge range according to age. An analysis performed by analysts at Imperial College in London, drawing from the Chinese experience, estimated that a quarter of those over 70 who contracted the disease in Great Britain and the United Kingdom would require hospitalisation. 

If the health system is overwhelmed in a country, and is unable to provide proper care to most patients with acute pneumonia, then the survival rate of those needing hospitalisation will drop precipitously.

II

One of the advantages South Africa has, relative to East Asian and European countries, is the young age of the population. 59,1% of the South African population is under 30 years of age. 87,6% under the age of 50.

Table 3: Age profile of the South African population by numbers

Age-groupBlack AfricanColouredIndian/AsianWhiteRSA
0 to 9

9 838 467

952 930

195 951

484 037

11 471 385

10 to 19

8 542 208

860 253

179 296

506 148

10 087 904

20 to 29

8 812 127

864 308

234 687

531 635

10 442 757

30 to 39

8 428 586

791 846

281 140

607 565

10 109 138

40 to 49

5 113 227

627 611

224 610

665 577

6 631 025

50 to 59

3 353 082

554 459

176 177

643 842

4 727 560

60 to 69

2 112 537

340 095

124 241

577 724

3 154 597

70 to 79

920 609

142 276

65 298

419 504

1 547 687

80+

322 416

42 971

21 608

215 973

602 969

Total

47 443 259

5 176 750

1 503 007

4 652 006

58 775 022

***

Table 4: Age profile of the South African population by proportion

Age-group (years)Black AfricanColouredIndian/AsianWhiteRSA
0 to 9

20,7%

2,0%

0,4%

1,0%

24,2%

10 to 19

18,0%

16,6%

11,9%

10,9%

17,2%

20 to 29

18,6%

16,7%

15,6%

11,4%

17,8%

30 to 39

17,8%

15,3%

18,7%

13,1%

17,2%

40 to 49

10,8%

12,1%

14,9%

14,3%

11,3%

50 to 59

7,1%

10,7%

11,7%

13,8%

8,0%

60 to 69

4,5%

6,6%

8,3%

12,4%

5,4%

70 to 79

1,9%

2,7%

4,3%

9,0%

2,6%

80+

0,7%

0,8%

1,4%

4,6%

1,0%

Total

100,0%

100,0%

100,0%

100,0%

100,0%

Source: StatsSA, MYPE, 2019

Only 6% (3,5m) of the population is over the age of 65. This compares to Italy, which has a similar size population, where over-65’s make up 23% (14m) of the total population. According to advice published by Harvard University “People who are older and older people with chronic medical conditions, especially cardiovascular disease, high blood pressure, diabetes, and lung disease are more likely to have severe disease or death from COVID-19, and should engage in strict social distancing without delay. This is also the case for people or who are immunocompromised because of a condition or treatment that weakens their immune response.”

The most critical unknown about the looming Covid-19 epidemic in South Africa is how the disease will intersect with the massive number of TB and HIV/AIDS cases in the country. As the Academy of Sciences of South Africa recently noted, “it is not known whether individuals with Human Immunodeficiency Virus (HIV) or underlying Tuberculosis (TB), both of which are highly prevalent in South Africa, are at increased risk for severe disease following infection with SARS-CoV-2. This is especially relevant based on evidence that individuals living with HIV have an eight-fold greater burden of hospitalisation for pneumonia due to influenza virus, and a three-fold higher case fatality risk.”

According to World Health Organisation estimates the incidence (number of new cases) of TB in South Africa was around 301 000 in 2018, with HIV-positive TB incidence at around 177 000. In 2016 StatsSA estimated that TB (of either type) was the leading cause of death among South Africans. 29,399 of the 454 989 deaths recorded that year were attributed to this disease. The WHO though put the estimated number of deaths from TB at 63 000 in 2018.

The South African National HIV Prevalence, Incidence, Behaviour and Communication Survey, 2017 estimated that there were 7,9m South Africans living with HIV that year. Of these 4,4 million were on anti-retroviral treatment (ART), and 3,5 million not on treatment. Of those with HIV an estimated 4,9m had suppressed viral loads – a sign of effective treatment and/or immune response – while 3m did not.

HIV cases in South Africa in 2017 by age and treatment status.

Age group (years)HIV positiveOn ARTNot on ARTViral load suppressedViral load not suppressed
0–14

451 570

131 000

320 570

234 365

217 205

15–24

760 238

274 000

486 238

362 634

397 604

25–49

5 595 638

3 244 000

2 351 638

3 514 060

2 081 577

50 and older

1 122 282

753 000

369 282

821 510

300 772

Total

7 929 728

4 402 000

3 527 728

4 940 221

2 989 507

III

The probable situation now is that the SARS-CoV-2 is already present, and quietly spreading, in many different communities in South Africa. The symptoms being presented are mild, to non-existent, as the NICD has yet to start picking up on severe cases. To the extent that warm weather has provided a break on its spread and severity, this will be lifted once the first winter cold front sweeps across the country. While government measures announced by President Cyril Ramaphosa have concentrated the minds of South Africans, it is doubtful for how long the epidemic can be contained. For example, if one begins with 100 undetected internal cases, and the number doubles every three days (currently the rate of increase in some European countries), you will go from 100 cases to 100,000 in 30 days.

It is true that Singapore, Taiwan, Hong Kong and South Korea all managed to keep a lid on the epidemic in their countries. But these are all nations with highly effective states and disciplined societies which experienced, and learnt lessons from, the first SARS epidemic in 2002 and 2003. They reacted very quickly and effectively to this new, but familiar, coronavirus. They have combined social distancing with the ubiquitous wearing of masks in public, the testing of all those with symptoms, the quarantining of those who test positive, and highly aggressive and effective contact tracing. They are also all (in effect) island nations, able to now restrict entry across their borders, and thereby minimise the re-importation of the virus from overseas. Europe, Great Britain and the United States are stumbling far behind, still not knowing quite what to do.

A public health notice on the coronavirus in Hong Kong:

South Africa lacks the masks, the tests, and the necessary state capacity, and will do so through the course of the epidemic. If one region of the country were to halt the spread of the virus temporarily, it could be re-imported from any other. The living and transportation conditions of millions are crowded and awful. There are also ten million twenty-something South Africans. This is an age cohort that is highly social, and notoriously irresponsible. Unless there is some as yet unknown obstacle in the path of the virus – not present in Europe or Asia – it is likely to spread rapidly across the country. Beyond a certain point testing, contact tracing and quarantining people will become futile and redundant.

The best response to the coming winter flood is not to invest everything in trying to stop it, which may well ultimately prove impossible, but to (also) try and ensure that as many among the most vulnerable in society are on safer, higher ground. This includes medical workers, the elderly, those with pre-existing medical conditions, including those with TB, and those with immune deficiency.

Doctors and nurses need access to proper protective equipment. Old age homes need to develop strict protocols to keep out the virus. Elderly people and those with pre-existing medical conditions need to self-isolate. Employers should do whatever is necessary to minimise the chances that vulnerable employees – such as those being treated for TB (or with lungs damaged by TB) – become infected over the winter. If it is not already too late to do so the state should seriously encourage people to get tested for HIV and go onto ART.

It seems unlikely that the state and private healthcare systems – which may well merge to battle the crisis – will be able to cope at the epidemic’s peak. The Wits health economist Alex van den Heever was quoted in Business Day as estimating that there were approximately 4,960 critical care beds in the private sector in 2017, with 60% availability, and approximately 2,240 critical care beds in the state sector, with 20% availability.

This would mean that around 4 000 such beds are currently available for severe cases of Covid-19. Once the first person has to be hospitalised, and assuming the number of those so afflicted doubles every 2,3 days, then all those beds would be occupied within the space of a month. No-one can be confident then that there will be a critical care bed available for them should they develop severe illness over the winter.

IV

In such situations it is worth returning to the parable of the Sultan’s horse.

Two condemned prisoners were brought before the Sultan in fetters, one after another, to hear their fate. The Sultan addressed them, each in turn, as follows: “I am sentencing you to death by decapitation. However, I am willing to offer you a reprieve if you will teach my favourite horse to talk.”

The first prisoner indignantly replied: “What kind of choice is this? That is impossible!” “So be it”, replied the Sultan, and the man was dragged outside by the guards, to await his imminent execution.

A short while later he saw the second prisoner walk out of the room, a free man. Perplexed, the first prisoner asked him: “What did you tell the Sultan?”

The second man replied, “I said that I could certainly teach the horse to speak, but that it is an exceedingly difficult and time-consuming task, and it will take a year. He then said I could go free, but if I fail in my task I will be beheaded.”

The first prisoner exclaimed: “well, then you are most certainly doomed! No man has ever achieved that!”

To which the second man replied: “That is true. But a lot can happen in the year. Perhaps I will die peacefully in my sleep. Perhaps it is the Sultan himself who will die. Or perhaps even – who knows! – I will be the first to get such an animal to talk!”

South Africans, along with others around the world, are currently in the position of the two prisoners. There is neither a vaccine for SARS-CoV-2, nor a treatment for Covid-19. Humans lack immunity to it, and it is estimated that over half the world’s population will eventually contract it. For many of those over 60 it is a death sentence should they become infected.

The measures needed to temporarily check its spread cause acute economic and social distress.

Yet a lot is likely to happen over the next six months. Treatments will be developed and refined by researchers around the world. Progress will be made towards a vaccine. The understanding of the disease, how it is transmitted, and how to limit its spread, will rapidly develop.

If the epidemic runs largely unchecked in South Africa through winter the great majority of younger and healthy people will get the virus, develop only mild symptoms, and recover. They will thereby attain a degree of immunity which will, in aggregate, provide herd immunity to the broader society. This has the potential to bring a sustainable end to the epidemic in South Africa.

The important thing over the next six months is to do whatever it takes to protect yourself, if you are at high risk, and to protect and support others if you are not.

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