Should We Reconsider Herd Immunity?

4 April 2020. Updated 29 April 2020.

No product launch in history was botched as badly as herd immunity.  Introduced to the public on Friday March 13th in Sir Patrick Vallance’s media interviews, it enjoyed a short life before being pronounced dead and buried by the Sunday morning news shows.  First impressions last, and for most people hearing of the concept for the first time, its reputation was irrevocably tarnished. 

But its portrayal as an irresponsible, heartless policy to allow the disease to rampage indiscriminately through the country could not be more inaccurate.   Herd immunity has kept the human species alive for two million years. In the absence of a vaccine, herds (or populations, if you prefer) do not get wiped out by new viruses. Natural barriers are formed within the herd that contain and deprive the virus of space to expand.   Herd immunity is not a policy choice, in that it can’t be rejected and put back on the shelf. It will happen eventually, regardless of the interventions we make. It is a human conceit that we can control natural processes. Instead, rather like a martial art, the question is how to channel herd immunity to counter the virus. 

As Dr David L Katz argued in his New York Times article ‘Is our fight against coronavirus worse than the disease‘, the specific profile of COVID-19 lends itself to a herd immunity approach. The data “clearly points to clear and important risk differentials for severe coronavirus infection…based on age and prior health”. Unlike influenza, it does not kill children, meaning there’s very little risk of exposure for one of the most vulnerable groups in our societies. In the absence of a vaccine, a strategy of shielding the vulnerable, while allowing herd immunity to build amongst less vulnerable groups, can minimise the aggregate of direct and indirect costs. The current obsessive focus on a single metric –the number of deaths of people with COVID-19 – is counter-productive as it’s an incomplete measure of the true costs and benefits of policy choices. The impact on public health outcomes of poverty, lack of access to healthcare and basic services, will also have a massive, and currently unmeasured, effect. Katz proposes that policy choices should be based on “total harm minimisation”.

Swedish Professor Johan Giesecke, the first Chief Scientist of the European Center for Disease Prevention and Control, goes further. In a scathing interview, he challenges not only the assumptions behind Imperial College’s model and the UK policy choices based on that model, such as closing schools, but argues that the virus amounts to a “tsunami of a usually quite mild disease” that will wash over Europe regardless of the lockdown, with at least half of the population becoming infected. Public health policy choices by individual countries will, over time, have little impact on the number of deaths, but the costs of the lockdowns will far exceed those of a targeted strategy to protect the most vulnerable.  Giesecke goes further than Katz and considers the political as well as the economic costs, citing how Viktor Orban in Hungary has used the virus to suspend normal parliamentary democracy. (Our own Government isn’t far off doing that, either.) In an article from April 20th in China’s state propaganda organ Global Times, China clearly signals how it would like the crisis to end. It is entitled ‘Divisive US politics leads to democracy’s fast decay’.

It has now been six weeks since herd immunity was rejected, but it’s been happening in the background nonetheless. As Professor Ioannides of Stanford University has recently reported, based on serological tests for the presence of antibodies, the actual infection rate in the population may be 50 – 85x higher than the number of documented cases. The problem the UK now faces is how to quietly return to this strategy without alarming the public, having rejected it once for being too dangerous. Only with a holistic view of the costs and benefits of different policy choices we can make sensible decisions.

Further Reading

Herd immunity might still be key in the fight against coronavirus‘ by Matt Strauss, The Spectator, March 26th 2020

The free will of cavemen, herd immunity and the value of contrarian truth‘ by Barry Norris, Argonaut, March 30th 2020

PM’s virus adviser warns Britain might still need to adopt herd immunity in its fight against coronavirus as lockdown measures have “painted the country into a corner”‘ by Jack Elsum and Daniel Hussain, Daily Mail, April 4th 2020

Is our fight against coronavirus worse than the disease‘ by David L Katz, New York Times, March 20th 2020

Infect Everyone: How Herd Immunity Could Work for Poor Countries‘ by Ari Altstedter, Bloomberg News, April 22nd 2020

Coronavirus dies out within 70 days no matter how we tackle it, claims professor‘ by Sarah Knapton and Dominic Gilbert, The Telegraph, The Telegraph, April 23rd 2020

India should protect elderly and take herd immunity plunge: Thomas Friedman‘, India Today, April 28th 2020

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Mike May
Mike May
1 month ago

The WHO is warning that survival of COVID-19 does not necessary confer immunity, and a recent University of Buckingham study, among others, shows that some survivors, particularly at the younger end of the population, were found to have very low to zero SARS-CoV-2 antibody levels. However, if an individual survived it once then I’d say there’s a pretty good chance they can survive it again. In the light of this, the pathology I eventually expect to see exposed is that the younger population, with a stronger base immune system, is able to fight off the infection without producing antibodies, and it is only as people age that they need to produce antibodies to give their immune system a leg up.

Caswell Bligh
Caswell Bligh
1 month ago
Reply to  Mike May

Sarah Gilbert the Oxford vaccines expert was on the Marr show this morning. She said something along the lines of “The virus is very good at covering its tracks and not leaving much of a memory in the patient’s immune system”. Even she couldn’t say how long any antibodies or immunity would persist for. On the other hand, her vaccine provokes a much stronger immune response.

It’s looking to me as though antibody testing for the natural infection is increasingly going to be portrayed as a red herring. And natural herd immunity likewise – whether or not it is actually the case that there is sufficient natural immunity in the population to suppress the spread of the virus. The only thing that will satisfy these people is a universal vaccine that produces a clear, unambiguous marker to show that the citizen has complied with the state’s processing directives.

Sam
Sam
1 month ago
Reply to  Caswell Bligh

Vaccines are a good thing, not a conspiracy. As soon as there is a COVID-19 vaccine I will be finding a way to get it. But until there is a vaccine I want normal life, with the slightly increased chance of death from the virus, not some lockdown limbo of lost rights and poverty.

Chris Barron
Chris Barron
24 days ago
Reply to  Sam

Even if it hasn’t gone through proper efficacy testing ?

Thomas Pelham
Thomas Pelham
1 month ago
Reply to  Caswell Bligh

Surely if it’s not leaving much of a fingerprint in most people, that simply means that the antibody positives we do have are lower bounds? Given that antibody testing has found surprisingly high numbers in most of the studies thus found, isn’t that more proof that we’re closer to herd immunity and all the govt needs to do is manage the infection rate gently, not lock us down until a vaccine?

Grant
Grant
21 days ago
Reply to  Caswell Bligh

Well you won’t improve upon the immunity given by the natural virus. Vaccination is at best an imitation of the natural process. I would be be very wary of any claim that anyone’s vaccine offered better protection than having had the virus.

Martin Sewell
1 month ago

When an epidemic strikes and containment has failed, herd immunity is the inevitable outcome. But it makes sense to try and manage it. Reducing the rate of infection by intervening allows us to minimise the total number of people who get infected, reduce the peak number of infections and buy ourselves time.

Tim Bidie
Tim Bidie
1 month ago
Reply to  Martin Sewell

But it only makes sense if we have a clear view of when the epidemic struck. A Cambridge University study shows that the virus has been around in humans since mid September 2019. Some British universities have exchange programmes with Chinese universities, including Wuhan Institute of Technology. Students at UK universities returned to work around 25 September 2019.

Basing policy on modelling is a very bad idea if the data is flawed.

In this case, the data may very well be completely out of whack if the virus came to this country in September 2019 or shortly thereafter.

wendyk
wendyk
1 month ago

My feeling is that it has indeed spread far more widely than we’ve been led to believe: a friend recently told me that she’d experienced fatigue, headache and troublesome cough for about a fortnight, but thought no more about it.

Admittedly, she doesn’t follow the Covid news with any great interest, but nevertheless.

She is quite well, but obviously hasn’t been tested .

If many people have indeed had a few coughs and recovered ,isn’t it likely that Covid has been with us for some time and that many folk have not been troubled unduly?

It now appears that most deaths have struck those who are already ill, very old and frail, significantly obese and living in crowded households.

My small town is dying; businesses are closing, children are bored, young people are facing a bleak future.

Surely the lockdown could be eased to allow those of us who would prefer to resume a resemblance of normal life to take our chances, while nursing homes and the like continue to receive protection.

The economic and social consequences are becoming increasingly dire and the media continues to produce alarming bulletins.

Isn’t it likely that this virus will mutate and become less lethal?
A pathogen will achieve greater long term success if it doesn’t wipe out its hosts.

Finally, the rise in co- morbidity and opportunistic infections is manifesting, as many of us predicted: dental infections; missed cancer diagnoses; reduced screening programmes; diabetics missing essential podiatry appointments; anxiety and depression the inevitable results of loss of income and confinement in the home.

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