Clarifying semantic and policy confusion around responses to COVID-19 with notes on 'herd immunity'
https://www.channelnewsasia.com/news/commentary/covid-19-coronavirus-best-practices-singapore-success-strategy-12585706
This is an extremely sensible commentary by Hannah Clapham for the Singaporean cable and news channel, Channel News Asia. Not about what to do or how to do it, but trying to dispel some of the semantic and policy confusion around responses to the pandemic in different countries. Clapham is an assistant professor at the Saw Swee Hock School of Public Health at the National University of Singapore and was previously the head of modelling at the Oxford University Clinical Research Unit in Ho Chi Minh City. The whole article is well worth reading, I have excerpted the bits I think most relevant. All emphases in the text are mine.
"There has been much talk recently of the “herd immunity strategy”.Herd immunity is the indirect protection and subsequent reduction in cases brought about because a specified proportion of the population is immune to that disease.Herd immunity can be the outcome of a strategy or action, most sensibly, of vaccination. In the UK, however, herd immunity for COVID-19 has been discussed as the outcome of taking minimal action and letting many in the population get infected.
... A key issue in the discussion around the “herd immunity strategy” is one that has been seen more broadly in the COVID-19 response: Confusion around what a strategy is, versus what an action is and even what an outcome is....Here are other words that have been much used recently: Containment, suppression, mitigation. Are these actions, responses or outcomes? These words have each been used to mean all of the above, which has led to some confusion. For example, suppression is the outcome of having few cases in the population and keeping transmission under control. However, it has also been used to describe the strategy, even the actions taken to achieve this.
... let’s group things into four groups: outcomes, actions, constraints on these actions, and other consequences of these actions. Being clear-minded on these is critical in determining and communicating an effective coronavirus strategy.
1. UNDERSTANDING WHAT OUTCOMES WILL ARISE IF NOTHING IS DONE
Firstly let’s consider the action of inaction,... Initially we had the first few months of cases in Wuhan, then Italy, to assess what would happen if we did nothing.Drawing conclusions from my work and those of my colleagues around the world, using both mathematical and mental models, it is clear the outcome of inaction will be devastating both in terms of health outcomes and for the economy.
2. IDENTIFYING SPECIFIC OUTCOMES TO ALTER
...The preferable outcomes we should be aiming for.. are reductions in the number of infections, cases or deaths, but there are some subtleties within that.
Countries may want to develop a focus, whether reducing onward spread from imported cases, keeping case numbers low for a period of time (until vaccine available, for example), or ensuring that the number of cases needing hospitalisation, ventilators and ICU beds at any time is not higher than what is available at that time (essentially, flattening the curve).
3. LAYING OUT ACTIONS AND IDENTIFYING CONSTRAINTS
In order to achieve each outcome, there are a range of actions that can be taken. Some examples from around the world include physical distancing, movement restrictions (local, national and international), closing schools, testing and isolation of cases, contact tracing and isolation of individuals with underlying health conditions...We need to be clear about how each action is helping achieve the outcome. The actions listed above will limit the numbers of infections and cases.Other actions will alter the outcome in a slightly different way, by changing the healthcare capacity to deal with cases, for example, increasing numbers of beds or ventilators available, or by reducing burden of other diseases.
There are of course constraints on what actions can be taken, for example current testing capabilities, current contact tracing systems, social norms and what a population will follow, and authorities’ ability to enforce restrictions...Each country’s action have been taken within their own unique constraints and what has been deemed possible....These constraints may be real, but they may be moveableConstraints also must be viewed in the context of the outcome of inaction.
4. MAPPING OUT THE CONSEQUENCES OF ACTIONS
The actions taken to improve the outcome will also have other consequences. For physical distancing or movement restrictions, consequences will include isolation and loneliness, loss of income, more people needing to do online shopping and those with unstable home environments left at increased risk.For school closures, the consequences may include key workers staying home to look after children, or children spending more time with vulnerable grandparents. For both of these actions, there will also be wider economic impacts, particularly on smaller businesses. Some of these consequences feed directly back into the disease outcomes, for instance, if healthcare workers must stay at home to look after children, which has lead the UK to keep schools available only for children of key workers.
Other consequences do not impact the disease outcomes, but also must be responded to, for example the consequence of loss of income can be managed by government action of subsidies or universal basic income.
....We can clearly see the economic consequences of the actions taken to manage the coronavirus spread, however, the economic consequences of inaction are perhaps less clear.
It seems obvious, but perhaps researchers and policymakers need to do a better job of quantifying and communicating the impact on the economy when large numbers of people are seriously ill, deaths mount, and hospitals are overwhelmed.
This is an extremely sensible commentary by Hannah Clapham for the Singaporean cable and news channel, Channel News Asia. Not about what to do or how to do it, but trying to dispel some of the semantic and policy confusion around responses to the pandemic in different countries. Clapham is an assistant professor at the Saw Swee Hock School of Public Health at the National University of Singapore and was previously the head of modelling at the Oxford University Clinical Research Unit in Ho Chi Minh City. The whole article is well worth reading, I have excerpted the bits I think most relevant. All emphases in the text are mine.
"There has been much talk recently of the “herd immunity strategy”.Herd immunity is the indirect protection and subsequent reduction in cases brought about because a specified proportion of the population is immune to that disease.Herd immunity can be the outcome of a strategy or action, most sensibly, of vaccination. In the UK, however, herd immunity for COVID-19 has been discussed as the outcome of taking minimal action and letting many in the population get infected.
... A key issue in the discussion around the “herd immunity strategy” is one that has been seen more broadly in the COVID-19 response: Confusion around what a strategy is, versus what an action is and even what an outcome is....Here are other words that have been much used recently: Containment, suppression, mitigation. Are these actions, responses or outcomes? These words have each been used to mean all of the above, which has led to some confusion. For example, suppression is the outcome of having few cases in the population and keeping transmission under control. However, it has also been used to describe the strategy, even the actions taken to achieve this.
... let’s group things into four groups: outcomes, actions, constraints on these actions, and other consequences of these actions. Being clear-minded on these is critical in determining and communicating an effective coronavirus strategy.
1. UNDERSTANDING WHAT OUTCOMES WILL ARISE IF NOTHING IS DONE
Firstly let’s consider the action of inaction,... Initially we had the first few months of cases in Wuhan, then Italy, to assess what would happen if we did nothing.Drawing conclusions from my work and those of my colleagues around the world, using both mathematical and mental models, it is clear the outcome of inaction will be devastating both in terms of health outcomes and for the economy.
2. IDENTIFYING SPECIFIC OUTCOMES TO ALTER
...The preferable outcomes we should be aiming for.. are reductions in the number of infections, cases or deaths, but there are some subtleties within that.
Countries may want to develop a focus, whether reducing onward spread from imported cases, keeping case numbers low for a period of time (until vaccine available, for example), or ensuring that the number of cases needing hospitalisation, ventilators and ICU beds at any time is not higher than what is available at that time (essentially, flattening the curve).
3. LAYING OUT ACTIONS AND IDENTIFYING CONSTRAINTS
In order to achieve each outcome, there are a range of actions that can be taken. Some examples from around the world include physical distancing, movement restrictions (local, national and international), closing schools, testing and isolation of cases, contact tracing and isolation of individuals with underlying health conditions...We need to be clear about how each action is helping achieve the outcome. The actions listed above will limit the numbers of infections and cases.Other actions will alter the outcome in a slightly different way, by changing the healthcare capacity to deal with cases, for example, increasing numbers of beds or ventilators available, or by reducing burden of other diseases.
There are of course constraints on what actions can be taken, for example current testing capabilities, current contact tracing systems, social norms and what a population will follow, and authorities’ ability to enforce restrictions...Each country’s action have been taken within their own unique constraints and what has been deemed possible....These constraints may be real, but they may be moveableConstraints also must be viewed in the context of the outcome of inaction.
4. MAPPING OUT THE CONSEQUENCES OF ACTIONS
The actions taken to improve the outcome will also have other consequences. For physical distancing or movement restrictions, consequences will include isolation and loneliness, loss of income, more people needing to do online shopping and those with unstable home environments left at increased risk.For school closures, the consequences may include key workers staying home to look after children, or children spending more time with vulnerable grandparents. For both of these actions, there will also be wider economic impacts, particularly on smaller businesses. Some of these consequences feed directly back into the disease outcomes, for instance, if healthcare workers must stay at home to look after children, which has lead the UK to keep schools available only for children of key workers.
Other consequences do not impact the disease outcomes, but also must be responded to, for example the consequence of loss of income can be managed by government action of subsidies or universal basic income.
....We can clearly see the economic consequences of the actions taken to manage the coronavirus spread, however, the economic consequences of inaction are perhaps less clear.
It seems obvious, but perhaps researchers and policymakers need to do a better job of quantifying and communicating the impact on the economy when large numbers of people are seriously ill, deaths mount, and hospitals are overwhelmed.