Population ("herd") immunity

A minority of scientists have put forward the idea of allowing the covid-19 virus to spread throughout the community while attempting to shield the most vulnerable, in order to produce population immunity ("herd immunity").


This is not in accord with mainstream science, and the many objections to the proposal have been set out in an Independent SAGE document [1]:



Recently the Barrington group have signed a Declaration [2], advocating "Focused Protection". The text is reproduced below, and contentious sections have been highlighted and annotated with objections and queries (hover over the highlights).



The Great Barrington Declaration

As infectious disease epidemiologists and public health scientists we have grave concerns about the damaging physical and mental health impacts of the prevailing COVID-19 policies, and recommend an approach we call Focused Protection.

Coming from both the left and right, and around the world, we have devoted our careers to protecting people. Current lockdown policies are producing devastating effects on short and long-term public health. The results (to name a few) include lower childhood vaccination rates, worsening cardiovascular disease outcomes, fewer cancer screenings and deteriorating mental health – leading to greater excess mortality in years to come, with the working class and younger members of society carrying the heaviest burden.
Keeping students out of school is a grave injustice.One of the worst injustices in education is the plight of special needs students and other high-risk children who are not being educated [3], and this would get worse under the "Focused Protection" proposal.
How long would this last?


Keeping these measures in place until a vaccine is available will cause irreparable damage, with the underprivileged disproportionately harmed.It is completely unnecessary to keep lockdown measures in place. We just need to look at the evidence from the countries with good outcomes, and replace the chaotic centralised UK test and trace system by a high quality localised find-test-trace-isolate-support system as good as the best in the world.
Why is there no mention of testing?


Fortunately, our understanding of the virus is growing.
We know that vulnerability to death from COVID-19 is more than a thousand-fold higher in the old and infirm than the young. Indeed, for children, COVID-19 is less dangerous than many other harms, including influenza. There might be a thousand-fold difference between the two extremes, but this does not mean that there is a simple dichotomy - in reality, there is of a range of risks - there are not two separate groups of low risk and high risk.


As immunity builds in the population,We don't know how or if immunity would build up in the population because we don't know how long immunity lasts in those who have been infected. it may be as little as one year [1] - some cases of re-infection have already occurred within 6 months [1] - and so there could be continuing cycling infections without population immunity ever being achieved.
the risk of infection to all – including the vulnerable – falls.
We know that all populations will eventually reach herd immunityThis is wrong - we did not reach population immunity with many infectious diseases that have been a problem for mankind for centuries, such as plague, cholera, malaria, measles, and TB - and more recently outbreaks of SARS and Ebola have been eliminated by public health measures with only a tiny proportion of the population affected.
– i.e. the point at which the rate of new infections is stable – and that this can be assisted by (but is not dependent upon) a vaccine. Our goal should therefore be to
minimize mortalityIt is not just mortality that is the problem in the young and the old, but also symptoms of chronic fatigue that can last for months ("long covid"), and heart and lung problems, which may potentially lead on to long-term disability, as happens with polio.
Why is there no mention of "long covid"?
and social harm until we reach herd immunity.

The most compassionate approach that balances the risks and benefits of reaching herd immunity, is to allow those who are at minimal risk of death to live their lives normally to build up immunity to the virus through natural infection, while better protecting those who are at highest risk. Why is there no mention of suppression of the virus by efficient testing, tracing of contacts and isolating and supporting, with either no or very limited lockdowns?
This has been very effective in minimising both health and economic damage in New Zealand, South Korea, and elsewhere - and in Europe, it is the basis of Germany's good response [1].
Those countries with the least health effects have also had the least economic damage [4].
We call this Focused Protection.

Adopting measures to
protect the vulnerable Who are "the vulnerable"? What would the criteria be?
Is it just those with the thousand-fold increase in risk compared to the young, or does it also include those with any of the known risk factors such as obesity? This would be over 20% of the population [1]
should be the central aim of public health responses to COVID-19. By way of example,
nursing homes should use staff with acquired immunityThis does not sound realistic.
How many nursing homes can use only staff with acquired immunity?
Have nursing homes been consulted?
and perform frequent PCR testing of other staff and all visitors. Staff rotation should be minimized.
Retired people living at home should have groceries and other essentials delivered to their home.Would vulnerable people be unable to attend hospital appointments, dentists and optometrists?
Would they be prevented from receiving any medical care including in emergencies - or would they have to suffer worse outcomes in the event of admission to hospital where they would probably pick up covid-19 which would be circulating among the staff?
What would happen to people who are receiving social care in their own home?
When possible, they should meet family members outside rather than inside.
A comprehensive and detailed list of measures, including approaches to multi-generational households, can be implemented, and is well within the scope and capability of public health professionals.Where has a "comprehensive and detailed list of measures" been published?
Proposals for population immunity have been circulating since March, and so there has been ample time for one to have been drawn up. Has one actually been published?
If so, where?
If not, why not, and when will it be published?


Those who are not vulnerable should immediately be allowed to resume life as normal.What should happen in those households that are mixtures of non-vulnerable and vulnerable?
Would grandparents have to stop being involved in childcare?
Simple hygiene measures, such as hand washing and staying home when sick should be practiced by everyone to reduce the herd immunity threshold.
Schools and universities should be open for in-person teaching. Extracurricular activities, such as sports, should be resumed. Young low-risk adults should work normally, rather than from home. Restaurants and other businesses should open. Arts, music, sport and other cultural activities should resume.What would happen to vulnerable workers in these occupations?
Would they stay at home or be forced to work and contract the virus?
If they stay at home, how would these sectors of the economy function with so many workers missing?
People who are more at risk may participate if they wish, while society as a whole enjoys the protection conferred upon the vulnerable by those who have built up herd immunity.


Collected highlighted sections with comments

Keeping students out of school is a grave injustice.
One of the worst injustices in education is the plight of special needs students and other high-risk children who are not being educated [3], and this would get worse under the "Focused Protection" proposal.
How long would this last?
Keeping these measures in place until a vaccine is available will cause irreparable damage, with the underprivileged disproportionately harmed.
It is completely unnecessary to keep lockdown measures in place. We just need to look at the evidence from the countries with good outcomes, and replace the chaotic centralised UK test and trace system by a high quality localised find-test-trace-isolate-support system as good as the best in the world.
Why is there no mention of testing?
We know that vulnerability to death from COVID-19 is more than a thousand-fold higher in the old and infirm than the young. Indeed, for children, COVID-19 is less dangerous than many other harms, including influenza.
There might be a thousand-fold difference between the two extremes, but this does not mean that there is a simple dichotomy - in reality, there is of a range of risks - there are not two separate groups of low risk and high risk.
As immunity builds in the population,
We don't know how or if immunity would build up in the population because we don't know how long immunity lasts in those who have been infected. it may be as little as one year [1] - some cases of re-infection have already occurred within 6 months [1] - and so there could be continuing cycling infections without population immunity ever being achieved.
We know that all populations will eventually reach herd immunity
This is wrong - we did not reach population immunity with many infectious diseases that have been a problem for mankind for centuries, such as plague, cholera, malaria, measles, and TB - and more recently outbreaks of SARS and Ebola have been eliminated by public health measures with only a tiny proportion of the population affected.
minimize mortality
It is not just mortality that is the problem in the young and the old, but also symptoms of chronic fatigue that can last for months ("long covid"), and heart and lung problems, which may potentially lead on to long-term disability, as happens with polio.
Why is there no mention of "long covid"?
The most compassionate approach that balances the risks and benefits of reaching herd immunity, is to allow those who are at minimal risk of death to live their lives normally to build up immunity to the virus through natural infection, while better protecting those who are at highest risk.
Why is there no mention of suppression of the virus by efficient testing, tracing of contacts and isolating and supporting, with either no or very limited lockdowns?
This has been very effective in minimising both health and economic damage in New Zealand, South Korea, and elsewhere - and in Europe, it is the basis of Germany's good response [1].
Those countries with the least health effects have also had the least economic damage [4].
protect the vulnerable
Who are "the vulnerable"? What would the criteria be?
Is it just those with the thousand-fold increase in risk compared to the young, or does it also include those with any of the known risk factors such as obesity? This would be over 20% of the population [1]
nursing homes should use staff with acquired immunity
This does not sound realistic.
How many nursing homes can use only staff with acquired immunity?
Have nursing homes been consulted?
Retired people living at home should have groceries and other essentials delivered to their home.
Would vulnerable people be unable to attend hospital appointments, dentists and optometrists?
Would they be prevented from receiving any medical care including in emergencies - or would they have to suffer worse outcomes in the event of admission to hospital where they would probably pick up covid-19 which would be circulating among the staff?
What would happen to people who are receiving social care in their own home?
A comprehensive and detailed list of measures, including approaches to multi-generational households, can be implemented, and is well within the scope and capability of public health professionals.
Where has a "comprehensive and detailed list of measures" been published?
Proposals for population immunity have been circulating since March, and so there has been ample time for one to have been drawn up. Has one actually been published?
If so, where?
If not, why not, and when will it be published?
Those who are not vulnerable should immediately be allowed to resume life as normal.
What should happen in those households that are mixtures of non-vulnerable and vulnerable?
Would grandparents have to stop being involved in childcare?
Schools and universities should be open for in-person teaching. Extracurricular activities, such as sports, should be resumed. Young low-risk adults should work normally, rather than from home. Restaurants and other businesses should open. Arts, music, sport and other cultural activities should resume.
What would happen to vulnerable workers in these occupations?
Would they stay at home or be forced to work and contract the virus?
If they stay at home, how would these sectors of the economy function with so many workers missing?


References
[1]Independent SAGE (Sep 2020) A deliberate "population immunity" strategy before a vaccine: Why it wouldn’t work and why it shouldn’t be tried https://www.independentsage.org/wp-content/uploads/2020/09/population_immunity_FINALb.pdf
[2]https://gbdeclaration.org/#read
[3]Pupils with special needs 'forgotten' as English schools reopen (Sep 2020) https://www.theguardian.com/education/2020/sep/04/special-needs-pupils-forgotten-english-schools-reopen
[4]Greg Jericho The Guardian (12 Sep 2020) Regardless of Covid restrictions, if people are dying in large numbers your economy is stuffed https://www.theguardian.com/business/commentisfree/2020/sep/13/regardless-of-covid-restrictions-if-people-are-dying-in-large-numbers-your-economy-is-stuffed


More information at
Prof Anthony Costello: https://twitter.com/globalhlthtwit/status/1313833271558631425
Dr Zoe Hyde / Prof Devi Sridhar: https://twitter.com/DrZoeHyde/status/1309886580467798018



First published: 7 Oct 2020
Last updated: 10 Oct 2020