Prof Robert Booy: Vaccinations, Herd Immunity, and the Delta Variant

My guest this week is Prof Robert Booy, an infectious diseases paediatrician who works at the University of Sydney in vaccinology, epidemiology and infectious diseases. In our conversation we discuss the varied perspectives on the pandemic, the delta variant, how vaccines work, AstraZeneca and clotting risks, along with what the future might look like when it comes to vaccine passports and achieving herd immunity.

Health Podcast Highlights

Prof Robert Booy: Vaccinations, Herd Immunity, and the Delta Variant Introduction

The pandemic, it’s not a subject that I have directly dealt with on the podcast, although I have very indirectly dealt with it in many of the episodes that I have done on immune function with Andrew Saul, with Richard Cheng, with Michael Gonzalez, with Thomas Levy. In fact, anything that we have ever mentioned about improving your health is relevant to this pandemic. So improving immune function is critically important.

But we are also hearing a lot about vaccinations and the importance of vaccinations will play in us getting back to normal. And whether you like it or not, whether you’ve been a regular flu vaccinator or not, the simple fact is that this is the reality in which we find ourselves. So today my guest is Professor Robert Booy.

Robert will help us answer some of those questions. Robert is an Infectious Diseases Paediatrician. Since 2005, he has worked at the University of Sydney in the fields of Vaccinology, Epidemiology, and Infectious Diseases, which makes him an excellent person to ask about all of those things that we are currently living through.

He’s currently a senior professorial fellow at the University of Sydney’s Children’s Hospital in Westmead Clinical School. And from 2005 to 2009, he held the position of Head of Clinical Research at the National Centre for Immunisation Research and Surveillance at Westmead Children’s Hospital and remains an affiliate of that organisation today. I hope you enjoy this conversation I had with Professor Robert Booy.

Podcast Transcript

Dr Ron Ehrlich: [00:00:00] I’d like to acknowledge the traditional custodians of the land on which I am recording this podcast, the Gadigal people of the Eora Nation, and recognise their continuing connection to lands, water, and culture. I pay my respects to their elders of the past, present, and emerging.

Dr Ron Ehrlich: [00:00:27] Hello and welcome to Unstress. My name is Dr Ron Ehrlich. Well, the pandemic, it’s not a subject that I have directly dealt with on the podcast, although I have very indirectly dealt with it in many of the episodes that I have done on immune function with Andrew Saul, with Richard Cheng, with Michael Gonzalez, with Thomas Levy. In fact, anything that we have ever mentioned about improving your health is relevant to this pandemic. So improving immune function is critically important.

But we are also hearing a lot about vaccinations and the importance of vaccinations will play in us getting back to normal. And whether you like it or not, whether you’ve been a regular flu vaccinator or not, the simple fact is that this is the reality in which we find ourselves. So today my guest is Professor Robert Booy.

Dr Ron Ehrlich: [00:01:26] Robert will help us answer some of those questions. Robert is an Infectious Diseases Paediatrician. Since 2005, he has worked at The University of Sydney in the fields of Vaccinology, Epidemiology, and Infectious Diseases, which makes him an excellent person to ask about all of those things that we are currently living through.

He’s currently a senior professorial fellow at The University of Sydney’s Children’s Hospital in Westmead Clinical School. And from 2005 to 2009, he held the position of Head of Clinical Research at the National Centre for Immunisation Research and Surveillance at Westmead Children’s Hospital and remains an affiliate of that organisation today. I hope you enjoy this conversation I had with Professor Robert Booy. Welcome to the show, Robert.

Prof Robert Booy: [00:02:26] Really nice to be with you, Ron.

Dr Ron Ehrlich: [00:02:27] Robert, thank you so much for joining us, particularly at this time. I’m really interested. I’ve got a few questions, quite a few questions I want to ask you. But the big one, from your perspective and your experience in public health, vaccinations, past pandemics, how are you seeing this pandemic? How are you seeing it playing out?

Perspectives on the pandemic

Prof Robert Booy: [00:02:48] This is a pandemic like no other. It really has bothered the world in a big way. We look back to a century ago when we had the Influenza pandemic and 50 million people died. And so far we’re approaching five million deaths with this pandemic. Given that we have so much better medicine and vaccines to approach five million, it’s probably a bit like having 50 million dies. This is a real pandemic that is worthy of our attention. And for the first time in scientific history, we’ve developed a vaccine in real-time, which is effective and which is safe.

Dr Ron Ehrlich: [00:03:23] Well, I mean, I know that this is a little side here from that comment, but I know the lead times on these are usually much longer. Is this a function of collaboration, resources? How have we fast-tracked it so quickly?

Prof Robert Booy: [00:03:39] What’s been extraordinary is that so many people have worked together across different disciplines and huge amounts of government and industry money have been thrown at the problem. And the combination of all of that money and time and expertise means that we’ve developed not just one vaccine, but half a dozen different types of vaccines in absolutely record time.

Normally, it would take at a very minimum, five years to develop a new vaccine and preferably 10+ years to get all the ducks in a row. But this has been done in a year. It’s quite extraordinary.

Dr Ron Ehrlich: [00:04:12] Robert, we hear about this Delta variant. Why is the Delta variant so dangerous? 

Why is the Delta variant so dangerous?

Prof Robert Booy: [00:04:19] The Delta variant is just so much more transmissible. If you talk about a term called the Effective Reproduction Number, that is one person in the community, how many do they affect if they themselves are infected? That is, if you have one person who’s infected in the community, how many new people will they infect over the course of a few days? Well, it used to be said to be three, maybe four. Now it’s six, seven, or eight. But that’s an extraordinary number.

It’s up there with measles, which is highly transmissible with other infections like Pertussis Whooping Cough, which is highly transmissible. That makes it incredibly harder to control. Not only is there a problem with the number of people who could be infected, but also when you become infectious, one or even two days before you develop symptoms, you can pass this virus on to people near and dear to you or even people in the community with whom you’re shopping or going to work.

Dr Ron Ehrlich: [00:05:18] The mode of transmission is also clearly important, and that’s what I guess makes this Delta so, so, so contagious. Can you remind us a bit about the various ways in which viruses can be transmitted?

Prof Robert Booy: [00:05:35] The mode of transmission is multiple, so it’s not a mode that modes obviously a respiratory virus will pass through the air, a fine mist can go for a metre or to. Touch. If you contaminate your hands from your nose and mouth, you can then through touch, transmit infection. 

And then there are droplets which don’t go quite as far as a fine mist. But they then go through the air and they can fall onto nearby surfaces. And if they’re not regularly cleaned, someone who subsequently touches that surface within the next hour or two or three can acquire infection. So there’s a lot of ways. 

Close personal contact. It’s obviously important whether it’s through respiratory route, through touch or even self contamination, where you take the virus from your hands up to your mouth or nose or throat or your eyes. That’s another way that it transmits from a phone line, that’s from an inanimate object.

Dr Ron Ehrlich: [00:06:36] And as an aerosol, how long is it now? How long is it contagious? Within an aerosol space? Within an air space?

Prof Robert Booy: [00:06:45] Contagiousness is not just a simple equation, varies by time and place. So if there’s a mist in the air, it could be highly infectious for a few seconds or minutes and unless infectious after a few hours. So it’s not just a matter of where and how, but for how long and what the density of the viral contamination of the air or surfaces is heavy contamination or not.

Dr Ron Ehrlich: [00:07:14] Now, we started with the Alpha and we’re up to the Delta. I’m not sure whether I remember the Beta and Gamma in between, but can we expect the Epsilon, the Zeta, you know, can we work our way through the Greek alphabet here with variants? Is that what we can expect?

Can we expect other variants to emerge?

Prof Robert Booy: [00:07:31] When we have Alpha, and that’s not the start. The start was the variance in China. And then Alpha came along after that and especially affected places like the UK where it was observed that it was at least 50% more transmissible. Beta is a problem that started in South Africa, Gamma in Brazil, Delta is the new problem. And Delta is even more transmissible and is already Delta+, which has extra mutations that’s been observed in the South Asian region. There’s already Epsilon, Lambda and we’ll have several more.

The issue is whether it’s a variant of interest and possibly a problem or whether it’s a variant of concern where we know that it’s either more transmissible or virulent or both, or whether it might be able to evade immunity from vaccination. What we’re facing is a standard viral mutation, which leads to differences. It’s now or never.

That means it’s a virus which copies itself poorly, its progeny, the baby viruses don’t look like their mum and dad. They look quite different. When I say quite different. They may have one mutation. About every two weeks in one kind of transmission, there’s a new mutation which may or may not lead to a change in the virus. What we’re worried about is the Omega 3, the end of the world strike. We’re not going to get that, but we are going to get new strains every three to four months.

Prof Robert Booy: [00:09:05] The Omega strain, which people know from movies, is something that is deadly and it can’t be controlled. Well, I believe we’ve done extremely well with vaccination and with all the social measures which reduce transmission and the combination of those two things.

I have got control of many parts of the world. If you look at a place like Taiwan, an island like Australia with about 25 million people, they had a Delta surge about a month before we got out in June and their Delta surge was under control by 9-10 weeks. So even Delta, which is highly transmissible, can be brought under control through vaccination, through social measures, and we can come out of this. What happens next after Delta?

Prof Robert Booy: [00:09:54] Well, Lambda is being described, for example, what viruses tend to do is that they mutate to a more transmissible but not necessarily a more virulent form. That means that they may slowly become more like a cold virus. We already know about four coronaviruses in the community, which just cause the common cold. And another problem that we even have to vaccinate against. Some people speculate that the 1890 Flu Pandemic might have been a Coronavirus. 

Although it looks as though this is the unique Coronavirus pandemic we’re experiencing and suffering from right now, it may be that in the late 1800s we had a previous Corona pandemic, and that’s a subject of research and of interest to people in this field.

Dr Ron Ehrlich: [00:10:48] There was, I know you were very, you were at the epicentre of the SARS-1. I think that was in 2005. And MERS, why aren’t we hearing about them anymore? Are they going extinct?


Prof Robert Booy: [00:11:00] We have been doing research through mass gathering medicine for the WHO to look at birds, which came along about seven years ago, and before that in 2003, we had SARS, which affected essentially Singapore, Hong Kong, China, and Canada. But through good social measures, no vaccine. They got that under control. That’s because its transmissibility was far lower. So with standard handwashing, masks, social distancing, et cetera, that virus, SARS, could be brought under control.

MERS only occurs occasionally. If probably got a reservoir in camels and we only really see it in Saudi Arabia. The MERS hasn’t gone, SARS seems to have gone. And this new SARS-CoV-2, the second type of SARS, otherwise known as COVID-19, is so very different in its biological behaviour, in its human interaction. 

What has happened over the time of the last 18 months or so is that COVID-19 infection has become much more adapted to the human respiratory tract that the virus finds it much easier to get into our respiratory cells, cause infection and then get out again as well at higher levels. So this virus is mutating. It is adapting to humans and it may well, the early evidence is there. And may well, becoming a bit less severe.

Dr Ron Ehrlich: [00:12:31] And that’s encouraging. Look, the vaccines and particularly the ones we seem to have access to, well, Pfizer and Moderna are new technologies with mRNA. And is it true AstraZeneca is also a new technology? I’m a little bit. Yeah, it is. It is a new technology.

Is AstraZeneca a new technology?

Prof Robert Booy: [00:12:49] Well, look, let me start again. The mRNA approach has actually been tried for nearly 30 years. And there’s been some fantastic progress at the bench side level in the laboratory. But we’ve never before adapted it to make a vaccine that’s been applied to billions of people. So although the mRNA technology has been around for 20-30 years, as has the viral vector approach was taken by AstraZeneca and also taken by Janssen and other companies as well.

Prof Robert Booy: [00:13:24] Both those approaches are products of the last 20 or so years, but neither has been applied at great levels. There is a vaccine developed against Ebola by the EU in 2020. So there was a little bit of experience there from the trials around the safety of children, pregnant women, and other adults regarding a platform using a viral vector. 

The viral vector generally used adenovirus, it could be another virus from humans or chimpanzees, could be type 5 or 24 or 6. There’s a number of serotypes that are used in different vaccines. But the technology, whether it’s a viral vector or whether it’s mRNA has been developed over the last 20 to 30 years and refined in just a year.

Dr Ron Ehrlich: [00:14:15] So the idea of that be it mRNA and the Pfizer and Moderna or DNA in the AstraZeneca, I think that’s true. The idea of getting into the cell is quite revolutionary, is it not?

Prof Robert Booy: [00:14:30] It is revolutionary to take over the factory of the cell by sending in a bit of genetic material called messenger RNA. When you send in the DNA, it just gets transcribed in the cell to mRNA. So ultimately the same approach is taken. The protein-making machinery of a cell which occurs outside the nucleus leads to the spike protein being developed and released by muscle cells so the human body itself is creating the vaccine within human cells. 

And then they’re expressed. And then the immune system, both the T cells, the cellular approach, and the humoral, otherwise known as the antibody approach. Both of those arms react strongly to the spike protein of the virus and make both antibodies and cellular protective responses.

Dr Ron Ehrlich: [00:15:29] Traditionally, the protein, be it from the vaccine or the inactivated virus would be floating around and the body would send out antibodies and start dealing with an immune response to it. But here we’re inside the cell itself.

Prof Robert Booy: [00:15:45] And that’s where the initial work is done. And then the proteins are released from the cell into the fluids, the lymph, and the bloodstream and then various immune affect your cells, B, they B cells and T cells then take on their roles.

What’s probably really interesting and also important is why is it that children are so mildly affected? And the first is the strong, innate immune response, immediate response. So these are cells, be thy dendritic cells or Langerhans cells. They’re really souped-up white cells that can recognise a danger signal on the virus and interact immediately within minutes and hours in order to control a viral infection or to respond to a vaccination. Now, this innate immunity is so much stronger in children than in adults that they get hardly any symptoms.

Secondly, they make a much better adaptive immune response. Their B cells and their T cells soup up. They ramp up quickly and effectively.

Prof Robert Booy: [00:16:59] Thirdly, children probably have fewer receptors in their throat for this by protein, the receptor in a human throat. It’s called ACE. A-C-E. Number two. And that receptor is probably less dense and less common in the throat of children. So for those three reasons, it’s thought that children fight the infection much more readily and so uncommonly get sick.

Now everyone talks about children getting admitted to hospital and dying in intensive care. Yes, that’s true. But it’s a tiny proportion. And what really illustrates that well is if you look at the United States data. Less than 500 children have died of COVID in the US. 600 000 adults have died. 

For every one child that’s died of COVID in the US, more than 1000 adults have died. That tells you we should be vaccinating adults. Children can be vaccinated when their turn comes, but their turn should come after adults, the elderly, the infirmed, the immunosuppressed. All of those people must be vaccinated first.

Prof Robert Booy: [00:18:10] What is our responsibility as a global citizen, as a globally responsible nation? Well, we should be distributing vaccines to their near neighbours who can’t afford to buy it themselves. We’ve just offered in Australia two and a half million doses of AstraZeneca to Indonesia, that would cover just over one million people. They have a 270 million population. We’re not offering very much. We need to do better.

As responsible world citizens, we can take up the challenge to help our near neighbours first who can’t afford vaccination themselves, and we can do that through the COVAX Facility set up by UNICEF, WHO and GAVI. And simply the COVAX Facility procures and distributes vaccines in countries where it’s needed. 

They have an objective of getting at least 20% of the population vaccinated for free through donations from countries as well as the general public. There is a facility, if you go to immunisation coalition, I’m on the front page of that. You can get give a donation to UNICEF Australia specifically to procure and distribute vaccines against COVID for people who really need it.

Prof Robert Booy: [00:19:30] In Indonesia, hundreds of children are actually dying every week right now. So although COVID is not a problem of children, if you have a country with crowding, with a poor vaccination uptake, a country with a religious festival where everyone went into the countryside recently and spread the virus from the cities to the country, a country where there’s malnutrition, and not as good a diet, you can have problems in children. So although I strongly feel we should wait with vaccinating children in a country like Australia, in Indonesia, it’s a different equation.

And here come two ideas at once: (1) Why don’t we give a free vaccine to someone else? Because we’ve had a free vaccine ourselves as part of the national programme. And we can do it through UNICEF Australia and we can get people protected who really need it. Not children in Australia, but children overseas.

Prof Robert Booy: [00:20:30] One more idea I have to say: (2) What causes trouble? How is the Delta virus causing so much trouble? Because it’s transmissible because it’s a nasty virus and because it mutates. And mutation occurs when it’s replicating in the human body. So if we can vaccinate the people who would otherwise get a severe infection, if we can stop them from getting infected, or if we could at least minimise their symptoms, the transmission would be reduced. 

So although there’s an issue of sterilising immunity with measles and polio, we don’t have that here. But we do have a certain and sure hope that we can reduce transmission, reduce the viral load of the infected person, and ensure that they don’t end up in hospital or death. So we, by helping others, can help ourselves.

Dr Ron Ehrlich: [00:21:27] Robert, one of those things in the discussion about Pfizer, Moderna, or Janssen and all that, I must say I’m drawn particularly of all of them, to AstraZeneca, because they are not for profit and there is immediately an appealing aspect to this. What are your thoughts?

Prof Robert Booy: [00:21:44] I totally agree, Ron, the fact that AstraZeneca and Janssen are not for profit, and that means that a single dose is costing only about 2.50 dollars and two doses, that protection can be achieved with 5 Australian dollars. So if you gave, for example, 500 dollars to charity or UNICEF, you could save the lives of 100 people. If you gave 500 dollars, you could pay for a hundred of people in Indonesia to be vaccinated. It’s extraordinary to have a vaccine available, not for profit.

Pfizer, by contrast, is tens of dollars per dose, Pfizer and Moderna, mRNA vaccines are tens of dollars per dose. There are several billionaires just from the Pfizer and Moderna companies already. Billionaires. Though not for profit, it’s a great way forward to vaccinate people and make a difference. Payback, pay forward and give money to protect other people.

Dr Ron Ehrlich: [00:22:48] Now, you mentioned the word sterilising immunity. And I was going to ask you about vaccines like measles, mumps, rubella, smallpox, because as far as I understood it, and I could be wrong here, that that prevents us from contracting the disease and then passing it on. Is that right?

How do vaccines work?

Prof Robert Booy: [00:23:07] That’s right, Ron. What happens is that viruses like polio and measles and rubella that they only have one serotype, they don’t change. If you have a vaccine against measles or rubella or polio, it’s very effective because not only does it prevent disease, but it also prevents infection and therefore prevents transmission. So that’s fantastic. 

And the reason our immune system could act so well is because there’s only one serotype. It doesn’t have to constantly change your immunity, like against flu, which is mutating all the time and the RNA virus, which changes its spots and for which we can’t get sterilising immunity.

So sterilising immunity is nirvana. Not only do you prevent disease, but you prevent infection, prevent transmission, and you can get very close to eradication, where only a handful of cases per year of eradication of polio in many parts of the world are declared measles eliminated. So elimination is local, eradication is worldwide. So with those viruses, that’s a tremendous advance. We won’t be able to do that with Corona because the vaccines are not sterilising. But boy, they work well.

Dr Ron Ehrlich: [00:24:28] I think the hope that we will eventually end up with a vaccine for this, which gives us sterilising immunities, I hope to, that’s a bridge too far.

Prof Robert Booy: [00:24:41] Well, you’ve got an RNA virus-based disease. And although the coronavirus has actually a polymerase, which helps it to correct mistakes when it’s copying itself, it’s still imperfect and it doesn’t mutate on a daily basis the way flu does, but it does mutate on a weekly basis. So that’s still a problem.

Dr Ron Ehrlich: [00:25:02] What are the side effects? Are there any serious side effects with these COVID vaccines, even given the fact that I mean, we haven’t had them for very long, but how do we know? What should we be thinking there?

What are the side effects of COVID vaccines?

Prof Robert Booy: [00:25:15] We know a tremendous amount about the safety within days, weeks, and months. What we don’t know about is the safety after a year or two. If we go back to how we’ve understood other vaccines and their safety, we’ve learnt that the onset of side effects, adverse events is almost always within minutes, weeks, months, and not within years. It’s very unlikely we found, we don’t have evidence that you get side effects developing after a year or two.

Having said that, because the vaccines against Corona include mRNA, which we’ve never used before, we do have to do the due diligence. We do have to do the safety surveillance for a minimum of two to three years to be confident that there are longer term effects that occur after a year or two. If you haven’t done the surveillance, if you haven’t done the work, you don’t know the answer. And we haven’t had enough time since the viruses were developed to get the longer term safety profile. But from other vaccines, we know it’s most unlikely to get problems.

Prof Robert Booy: [00:26:26] What do we get within a month or so? What do we worry about as side effects of current vaccines? Well, the mRNA vaccines may produce in one in 100000 Anaphylaxis, an allergic reaction which causes swelling of the face and trouble breathing. But it’s almost always treatable and you survive. 

Also, about one in 100000 people can get Myocarditis, an inflammation of the heart muscle or the lining of the heart called Pericarditis. About 100000 are more common in young men and more common after the second dose. So that’s up to one in 25000 young men and more like 100000 across the population.

Dr Ron Ehrlich: [00:27:09] How is that dealt with?

AstraZeneca and Clotting risks

Prof Robert Booy: [00:27:10] So it’s managed by a cardiologist who will do an ECG and an echo and observe. There’s no specific treatment. People tend to get better of their own accord. Now, everyone is familiar with the rare clotting disorder that may be seen after viral vector vaccines have been seen at a rate of about 150 to 1 in 100000 after AstraZeneca especially the first dose. It’s also seen at a rate that may be close to 1 in 500000 after the Janssen product.

It is now much better recognised and it’s understood it’s due to the body producing antibodies against platelet factor 4 though platelets stick together because of antibodies and they clot. And so you get a Thrombocytopenia, a low platelet count, you get clots in places you shouldn’t get clots like dysplastic the abdomen, the chest, the brain, the cerebral venous sinuses. And these can be extremely serious and when first recognised, it caused 25-40% case fatality rate.

Prof Robert Booy: [00:28:12] Now, of course, it’s more like 2.5-4% fatality rate because it’s recognised earlier. It can be treated with effective treatment. And that includes not using effort, but another blood thinner and intravenous immunoglobulin, other people’s antibodies which settle down the inflammatory antibody-mediated problem. So GPs, emergency department doctors have become quite at adept and quick at recognising the syndrome, which occurs between four days and four weeks after the vaccine. 

So, you know, someone’s been vaccinated a short time ago. We recognise that there’s severe pain in the abdomen. Doesn’t seem right. Chest pain and breathlessness for the headache that doesn’t go away with usual analgesia. Any of those things lead to an investigation. You find the platelets are low, the ESR is up and a special test shows the antibody to the platelet back to number 4. 

So although that was a very worrying side effect to begin with, less so now, the risk of dying from AstraZeneca, a vaccine-induced Thrombosis, is somewhere close to one in a million. You’re more likely to die of being hit by lightning than to die of this thrombotic complication of atnovar expected vaccines like AstraZeneca and Janssen. 

Dr Ron Ehrlich: [00:29:39] You touched on this before. You mentioned about childhood vaccinations. And I’d love to, we will have links to those sites of support that you mentioned. But what are your thoughts? Should we vaccinate children against COVID? Can we touch on that a bit more?

What are your thoughts about vaccinating children against COVID?

Prof Robert Booy: [00:29:57] The vaccination of children against any disease should primarily be for their benefit to prevent the disease in the child. Trying to achieve herd immunity is a secondary approach where we vaccinate people not only for their immediate protection, but to stop them transmitting infection to other at-risk people, especially the immunosuppressed, the elderly. 

If the benefit to children is minimal, as it appears to be when vaccinating against COVID, let me give you an example. A whole year’s surveillance through the NHS in the United Kingdom has shown about 25 deaths in children from COVID. At the same time, they’ve had 125000 deaths in adults from COVID. So the routine vaccination of children on an annual basis could save perhaps 25 lives. Now, that’s comparable to routine vaccination benefits against bacterial meningitis like meningococcus.

We can save through routine vaccination in the UK somewhere between 25 and 50 lives per year. Universal vaccination is required to do that, and therefore you have to vaccinate hundreds of thousands of children across the board to get the benefit of saving 25 to 50 lives from bacterial meningitis or potentially from COVID. 

Will we still have another 25 deaths next year? Perhaps we will. Yes. Will we have more? Perhaps, but not likely. But a benefit to children of vaccination is really quite small and marginal. The benefit to the wider community could be substantial through herd immunity being achieved, not nearly enough adults have been vaccinated so far.

Prof Robert Booy: [00:31:44] We have to concentrate on adults. They’re the ones who we can prevent more deaths and diseases in. What we should be doing in regard to children is ensuring that those at risk, whether they’re adults, whether they’re children and adults overseas in a poor country like somewhere in Southern Africa. 

If we’re supporting the vaccination of children, not our own, but other people’s children, we’ll actually do everyone a favour, because by preventing infections at a huge level, you prevent the mutation of the virus. The virus mutates when it’s dividing and it divides in people who are infected. And then it divides in many thousands of others who are secondarily infected with the pandemic runs rampant through a country. 

So I believe we should delay vaccination of children for the moment until we vaccinate as many adults as possible in our own country until we’ve vaccinated and been generous enough to help the vaccination of countries around us and their neighbours who need our financial help and our expertise to procure and deliver vaccines and other treatments for COVID.

Dr Ron Ehrlich: [00:33:00] Robert, you’ve mentioned the word Herd Immunity. And we’ve heard it a lot. And it’s kind of the assumption is everybody knows what we’re talking about. I wonder if you might just for a moment, take a step back and give us what herd immunity means. Herd Immunity 101.

Herd Immunity & Vaccine Passports

Prof Robert Booy: [00:33:17] Herd immunity comes from veterinary practise. The herd of cattle are protected against a disease for two important reasons. First of all, the majority of them can be vaccinated. And ‘Vacca’ comes from the Latin word for cow. Another interesting corollary. However, if the majority of the herd is vaccinated, infection can’t get in. It comes up against a barrier. It can’t transmit because a kid comes up against sterilising immunity, a vaccinated cow that can’t get infected and can’t pass at all. 

Now, if 9 out of 10 cows are vaccinated, the one cow that’s at risk. What the mixing with the one that’s infected because there’s this big barrier, this prevention of the virus getting through. And so that is Herd Immunity. So that one cow who is susceptible does not even come into physical contact with the one cow that’s sick because all the other well cows will, cows, are in the way. 

Dr Ron Ehrlich: [00:34:26] Is that achievable, though, when you can’t achieve sterilising immunity?

Prof Robert Booy: [00:34:31] It’s much harder and it may not be achieved. Be that as it may, what we could achieve by getting 80% of people vaccinated is they’ll be protected. And that’s enormous. And what we do know is that perhaps we don’t get sterilising immunity, but what we get is reduced transmission, reduced infectious symptoms. And that takes us on the path to possible herd immunity and certainly takes us on a path to outbreaks occur. They’ll be short and small in number.

Dr Ron Ehrlich: [00:35:05] What do you think about the concept of a passport? A Vaccine Passport?

Prof Robert Booy: [00:35:11] Nudge Ala France says the French are doing it and they’re simply saying, if you want to go shopping, you want to go to the cinema, you want to go to a restaurant, you’re French. Well, you need to be protected against COVID and you need to have a passport which says you’ve been vaccinated or you’ve had a test in the last 24 hours that says you’re not infected or you’ve got a proven past history of having had the infection.

So for one of those three reasons, you can have a passport, you can do the things that you want to do. And the positive aspects of controlling this virus need to be emphasised just as much as the negative complications of the disease.

So the positive benefits of having a passport and being able to live a normal life again and the positive benefits of not getting sick and dying, all of those add up together. They don’t need an incentive. You don’t need to be in a lottery. The vaccine sells itself.

Dr Ron Ehrlich: [00:36:12] Now, I asked you about the children, and I was going to ask you also about pregnant women. What are your thoughts on the vaccination of pregnant women?

Are pregnant women safe for COVID vaccines?

Prof Robert Booy: [00:36:19] Pregnant women can get COVID quite severely, especially in the third trimester, just as women with Influenza have done in the past and still do. They need to be vaccinated against flu and the risk from COVID is even higher. What we have marvelous information on is hundreds of thousands of women vaccinated against COVID in the real world. 

Having had Pfizer overturn up in North America. And so we know from the experience already with hundreds of thousands of women over the course of weeks and months, that the vaccine is well tolerated, that it is effective, and studies will soon be published to confirm that and that baby’s health is protected and the mother’s health, too.

You can imagine a pregnant woman with a very full abdomen because they’ve got a placenta with fluid and a baby, and then that impinges on the physical state of being able to breathe. And if you’ve got a severe infection affecting your breathing and then you have a constriction produced by a baby, quite apart from other immunological issues, which might also be important, you can get a much more severe infection. And we learnt way back in 1919, a century ago, that in the third trimester, you were particularly at risk of a respiratory viral infection. That was the flu. And likewise, like COVID.

Dr Ron Ehrlich: [00:37:45] Hmm. Wow. Robert, thank you so much for joining us today and shedding some light on this very challenging time we find ourselves in. Thank you so much.

Prof Robert Booy: [00:37:57] You’re welcome. It’s been fine.


Dr Ron Ehrlich: [00:38:01] Well, I thought it would be a great opportunity to get somebody in the epicentre of this, and Robert has, as you gathered from the introduction, been working in this space for many years. And I was very grateful to him for sharing his time and expertise with us. It’s such an emotive time, such a confusing time. “Have you been vaccinated?” That’s the question everybody asks everybody. And to be honest, for me personally, I have never had a flu vaccine. And I hope that doesn’t shock Robert, but I never have.

But when it comes to this particular pandemic, I kind of feel like as a global citizen, the fact that you know, it’s clear that we are just not going to be getting back to normal, whatever normal means or was or will be unless we are vaccinated. And I thought it was interesting to draw that distinction between sterilising immunity, which is what measles, mumps, rubella, polio, smallpox is, which means you can actually eradicate a virus because the serotype of the virus doesn’t change. So it’s easier to vaccinate, whereas a Coronavirus, mRNA virus does mutate constantly. 

We’ve already had the Alpha Beta Gamma Delta, will work our way up the Greek Alphabet, as Robert mentioned, then we’re not going to have sterilising immunity but the idea of being vaccinated is that we don’t overwhelm our hospitals and intensive care units and we increase our chance of not being ill.

Dr Ron Ehrlich: [00:39:42] Now, you will know if you’re a regular listener, that I have also spent a great deal of time talking about immune function. And we should not forget the fact that improving your immune function is an excellent way of not only reducing your risk of Coronavirus complications but also death. 

And it’s also a great way of avoiding those other things like comorbidities, which we used to refer to as preventable chronic degenerative diseases like heart disease, cancer, autoimmune conditions and diabetes. So you’ve got to take a holistic view of it. And although I haven’t had a flu vaccine before, I am going to be vaccinated here.

And I’m drawn towards the AstraZeneca because of its not for profit nature of the fact that it doesn’t require being frozen, which kind of makes me think, my goodness, how sensitive is this material that’s about to be injected into me? I think the not for profit part is to me perhaps the most important part. And at the end of the day, even though I am, I’ve never been vaccinated for flu, I look at people in the hospitality and detainment, tourism industry and academia, and all these other places which we just have to support.

Dr Ron Ehrlich: [00:41:00] I’ve got plenty of friends that want to visit their relatives overseas and I’ve got plenty of relatives that I want to visit us. And so whether I like it or not, vaccination is the way that’s going to happen. And so that’s why I will get vaccinated. 

And so I wanted to share that with you. It’s as I’ve said to you before, the podcast is an opportunity for me to ask questions of people that know much more than I do, questions have them answer, and let me consider what they tell me. And I hope that’s been of some help to you. I hope this finds you well until next time. This is Dr Ron Ehrlich. Be well.


This podcast provides general information and discussion about medicine, health, and related subjects. The content is not intended and should not be construed as medical advice or as a substitute for care by a qualified medical practitioner. If you or any other person has a medical concern, he or she should consult with an appropriately qualified medical practitioner. Guests who speak in this podcast express their own opinions, experiences, and conclusions.