This post is part 4 of COVID-19 policy in the UK: Did the UK Government ‘follow the science’? Reflections on SAGE meetings
SAGE began a series of extraordinary meetings from 22nd January 2020. The first was described as ‘precautionary’ (22.1.20: 1) and includes updates from NERVTAG which met from 13th January. Its minutes state that ‘SAGE is unable to say at this stage whether it might be required to reconvene’ (22.1.20: 2). The second meeting notes that SAGE will meet regularly (e.g. 2-3 times per week in February) and coordinate all relevant science advice to inform domestic policy, including from NERVTAG and SPI-M (Scientific Pandemic Influenza Group on Modelling) which became a ‘formal sub-group of SAGE for the duration of this outbreak’ (SPI-M-O) (28.1.20: 1). It also convened an additional Scientific Pandemic Influenza subgroup (SPI-B) in February. I summarise these developments by month, but you can see that, by March, it is worth summarising each meeting. The main theme is uncertainty.
The first meeting highlights immense uncertainty. Its description of WN-CoV (Wuhan Coronavirus), and statements such as ‘There is evidence of person-to-person transmission. It is unknown whether transmission is sustainable’, sum up the profound lack of information on what is to come (22.1.20: 1-2). It notes high uncertainty on how to identify cases, rates of infection, infectiousness in the absence of symptoms, and which previous experience (such as MERS) offers the most useful guidance. Only 6 days later, it estimates an R between 2-3, doubling rate of 3-4 days, incubation period of around 5 days, 14-day window of infectivity, varied symptoms such as coughing and fever, and a respiratory transmission route (different from SARS and MERS) (28.1.20: 1). These estimates are fairly constant from then, albeit qualified with reference to uncertainty (e.g. about asymptomatic transmission), some key outliers (e.g. the duration of illness in one case was 41 days – 4.2.20: 1), and some new estimates (e.g. of a 6-day ‘serial interval’, or ‘time between successive cases in a chain of transmission’, 11.2.20: 1). By now, it is preparing a response: modelling a ‘reasonable worst case scenario’ (RWC) based on the assumption of an R of 2.5 and no known treatment or vaccine, considering how to slow the spread, and considering how behavioural insights can be used to encourage self-isolation.
SAGE began to focus on what measures might delay or reduce the impact of the epidemic. It described travel restrictions from China as low value, since a 95% reduction would have to be draconian to achieve and only secure a one month delay, which might be better achieved with other measures (3.2.20: 1-2). It, and supporting papers, suggested that the evidence was so limited that they could draw ‘no meaningful conclusions … as to whether it is possible to achieve a delay of a month’ by using one or a combination of these measures: international travel restrictions, domestic travel restrictions, quarantine people coming from infected areas, close schools, close FE/ HE, cancel large public events, contact tracing, voluntary home isolation, facemasks, hand washing. Further, some could undermine each other (e.g. school closures impact on older people or people in self-isolation) and have major societal or opportunity costs (SPI-M-O, 3.2.20b: 1-4). For example, the ‘SPI-M-O: Consensus view on public gatherings’ (11.2.20: 1) notes the aim to reduce duration and closeness of (particularly indoor) contact. Large outdoor gatherings are not worse than small, and stopping large events could prompt people to go to pubs (worse).
Throughout February, the minutes emphasize high uncertainty:
- if there will be an epidemic outside of China (4.2.20: 2)
- if it spreads through ‘air conditioning systems’ (4.2.20: 3)
- the spread from, and impact on, children and therefore the impact of closing schools (4.2.20: 3; discussed in a separate paper by SPI-M-O, 10.2.20c: 1-2)
- ‘SAGE heard that NERVTAG advises that there is limited to no evidence of the benefits of the general public wearing facemasks as a preventative measure’ (while ‘symptomatic people should be encouraged to wear a surgical face mask, providing that it can be tolerated’ (4.2.20: 3)
At the same time, its meeting papers emphasized a delay in accurate figures during an initial outbreak: ‘Preliminary forecasts and accurate estimates of epidemiological parameters will likely be available in the order of weeks and not days following widespread outbreaks in the UK’ (SPI-M-O, 3.2.20a: 3).
This problem proved to be crucial to the timing of government intervention. A key learning point will be the disconnect between the following statement and the subsequent realisation (3-4 weeks later) that the lockdown measures from mid-to-late March came too late to prevent an unanticipated number of excess deaths:
‘SAGE advises that surveillance measures, which commenced this week, will provide
actionable data to inform HMG efforts to contain and mitigate spread of Covid-19’ … PHE’s surveillance approach provides sufficient sensitivity to detect an outbreak in its early stages. This should provide evidence of an epidemic around 9- 11 weeks before its peak … increasing surveillance coverage beyond the current approach would not significantly improve our understanding of incidence’ (25.2.20: 1)
It also seems clear from the minutes and papers that SAGE highlighted a reasonable worst case scenario on 26.2.20. It was as worrying as the Imperial College COVID-19 Response Team report dated 16.3.20 that allegedly changed the UK Government’s mind on the 16th March. Meeting paper 26.2.20a described the assumption of an 80% infection attack rate and 50% clinical attack rate (i.e. 50% of the UK population would experience symptoms), which underpins the assumption of 3.6 million requiring hospital care of at least 8 days (11% of symptomatic), and 541,200 requiring ventilation (1.65% of symptomatic) for 16 days. While it lists excess deaths as unknown, its 1% infection mortality rate suggests 524,800 deaths. This RWC replaces a previous projection (in Meeting paper 10.2.20a: 1-3, based on pandemic flu assumptions) of 820,000 excess deaths (27.2.20: 1).
As such, the more important difference could come from SAGE’s discussion of ‘non-pharmaceutical interventions (NPIs)’ if it recommends ‘mitigation’ while the Imperial team recommends ‘suppression’. However, the language to describe each approach is too unclear to tell (see Theme 1. The language of intervention; also note that NPIs were often described from March as ‘behavioural and social interventions’ following an SPI-B recommendation, Meeting paper 3.2.20: 1, but the language of NPI seems to have stuck).
In March, SAGE focused initially (Meetings 12-14) on preparing for the peak of infection on the assumption that it had time to transition towards a series of isolation and social distancing measures that would be sustainable (and therefore unlikely to contribute to a second peak if lifted too soon). Early meetings and meeting papers express caution about the limited evidence for intervention and the potential for their unintended consequences. This approach began to change somewhat from mid-March (Meeting 15), and accelerate from Meetings 16-18, when it became clear that incidence and virus transmission were much larger than expected, before a new phase began from Meeting 19 (after the UK lockdown was announced on the 23rd).
Meeting 12 (3.3.18) describes preparations to gather and consolidate information on the epidemic and the likely relative effect of each intervention, while its meeting papers emphasise:
- ‘It is highly likely that there is sustained transmission of COVID-19 in the UK at present’, and a peak of infection ‘might be expected approximately 3-5 months after the establishment of widespread sustained transmission’ (SPI-M Meeting paper 2.3.20: 1)
- the need the prepare the public while giving ‘clear and transparent reasons for different strategies’ and reducing ambiguity whenever giving guidance (SPI-B Meeting paper 3.2.20: 1-2)
- The need to combine different measures (e.g. school closure, self-isolation, household isolation, isolating over-65s) at the right time; ‘implementing a subset of measures would be ideal. Whilst this would have a more moderate impact it would be much less likely to result in a second wave’ (Meeting paper 4.3.20a: 3).
Meeting 13 (5.3.20) describes staying in the ‘containment’ phase (which, I think, means isolating people with positive tests at home or in hospital) , and introducing: a 12-week period of individual and household isolation measures in 1-2 weeks, on the assumption of 50% compliance; and a longer period of shielding over-65s 2 weeks later. It describes ‘no evidence to suggest that banning very large gatherings would reduce transmission’, while closing bars and restaurants ‘would have an effect, but would be very difficult to implement’, and ‘school closures would have smaller effects on the epidemic curve than other options’ (5.3.20: 1). Its SPI-B Meeting paper (4.3.20b) expresses caution about limited evidence and reliance on expert opinion, while identifying:
- potential displacement problems (e.g. school closures prompt people to congregate elsewhere, or be looked after by vulnerable older people, while parents to lose the chance to work)
- the visibility of groups not complying
- the unequal impact on poorer and single parent families of school closure and loss of school meals, lost income, lower internet access, and isolation
- how to reduce discontent about only isolating at-risk groups (the view that ‘explaining that members of the community are building some immunity will make this acceptable’ is not unanimous) (4.3.20b: 2).
Meeting 14 (10.3.20) states that the UK may have 5-10000 cases and ‘10-14 weeks from the epidemic peak if no mitigations are introduced’ (10.3.20: 2). It restates the focus on isolation first, followed by additional measures in April, and emphasizes the need to transition to measures that are acceptable and sustainable for the long term:
‘SAGE agreed that a balance needs to be struck between interventions that theoretically have significant impacts and interventions which the public can feasibly and safely adopt in sufficient numbers over long periods’ …’the public will face considerable challenges in seeking to comply with these measures, (e.g. poorer households, those relying on grandparents for childcare)’ (10.3.20: 2)
Meeting 15 (13.3.20: 1) describes an update to its data, suggesting ‘more cases in the UK than SAGE previously expected at this point, and we may therefore be further ahead on the epidemic curve, but the UK remains on broadly the same epidemic trajectory and time to peak’. It states that ‘household isolation and social distancing of the elderly and vulnerable should be implemented soon, provided they can be done well and equitably’, noting that there are ‘no strong scientific grounds’ to accelerate key measures but ‘there will be some minor gains from going early and potentially useful reinforcement of the importance of taking personal action if symptomatic’ (13.3.20: 1) and ‘more intensive actions’ will be required to maintain NHS capacity (13.3.20: 2).
On the 16th March, the UK Prime Minister Boris Johnson describes an ‘emergency’ (one week before declaring a ‘national emergency’ and UK-wide lockdown)
Meeting 16 (16.3.20) describes the possibility that there are 5-10000 new cases in the UK (there is great uncertainty on the estimate’), doubling every 5-6 days. Therefore, to stay within NHS capacity, ‘the advice from SAGE has changed regarding the speed of implementation of additional interventions. SAGE advises that there is clear evidence to support additional social distancing measures be introduced as soon as possible’ (16.3.20: 1). SPI-M Meeting paper (16.3.20: 1) describes:
‘a combination of case isolation, household isolation and social distancing of vulnerable groups is very unlikely to prevent critical care facilities being overwhelmed … it is unclear whether or not the addition of general social distancing measures to case isolation, household isolation and social distancing of vulnerable groups would curtail the epidemic by reducing the reproduction number to less than 1 … the addition of both general social distancing and school closures to case isolation, household isolation and social distancing of vulnerable groups would be likely to control the epidemic when kept in place for a long period. SPI-M-O agreed that this strategy should be followed as soon as practical’
Meeting 17 (18.3.20) marks a major acceleration of plans, and a de-emphasis of the low-certainty/ beware-the-unintended-consequences approach of previous meetings (on the assumption that it was now 2-4 weeks behind Italy). It recommends school closures as soon as possible (and it, and SPIM Meeting paper 17.3.20b, now downplays the likely displacement effect). It focuses particularly on London, as the place with the largest initial numbers:
‘Measures with the strongest support, in terms of effect, were closure of a) schools, b) places of leisure (restaurants, bars, entertainment and indoor public spaces) and c) indoor workplaces. … Transport measures such as restricting public transport, taxis and private hire facilities would have minimal impact on reducing transmission’ (18.3.20: 2)
Meeting 18 (23.3.20) states that the R is higher than expected (2.6-2.8), requiring ‘high rates of compliance for social distancing’ to get it below 1 and stay under NHS capacity (23.3.20: 1). There is an urgent need for more community testing/ surveillance (and to address the global shortage of test supplies). In the meantime, it needs a ‘clear rationale for prioritising testing for patients and health workers’ (the latter ‘should take priority’) (23.3.20: 3) Closing UK borders ‘would have a negligible effect on spread’ (23.3.20: 2).
The lockdown. On the 23rd March 2020, the UK Prime Minister Boris Johnson declared: ‘From this evening I must give the British people a very simple instruction – you must stay at home’. He announced measures to help limit the impact of coronavirus, including police powers to support public health, such as to disperse gatherings of more than two people (unless they live together), close events and shops, and limit outdoor exercise to once per day (at a distance of two metres from others).
Meeting 19 (26.3.20) follows the lockdown. SAGE describes its priorities if the R goes below 1 and NHS capacity remains under 100%: ‘monitoring, maintenance and release’ (based on higher testing); public messaging on mass testing and varying interventions; understanding nosocomial transmission and immunology; clinical trials (avoiding hasty decisions’ on new drug treatment in absence of good data) and ‘how to minimise potential harms from the interventions, including those arising from postponement of normal services, mental ill health and reduced ability to exercise. It needs to consider in particular health impacts on poorer people’ (26.3.20: 1-2). The optimistic scenario is 10,000 deaths from the first wave (SPIM-O Meeting paper 25.3.20: 4).
Meeting 20 Confirms RWC and optimistic scenarios (Meeting paper 25.3.20), but it needs a ‘clearer narrative, clarifying areas subject to uncertainty and sensitivities’ and to clarify that scenarios (with different assumptions on, for example, the R, which should be explained more) are not predictions (29.3.20).
Meeting 21 seeks to establish SAGE ‘scientific priorities’ (e.g. long term health impacts of COVID-19, including socioeconomic impact on health (including mental health), community testing, international work (‘comorbidities such as malaria and malnutrition) (31.3.20: 1-2). NHS to set up an interdisciplinary group (including science and engineering) to ‘understand and tackle nosocomial transmission’ in the context of its growth and urgent need to define/ track it (31.3.20: 1-2). SAGE to focus on testing requirements, not operational issues. It notes the need to identify a single source of information on deaths.
The meetings in April highlight four recurring themes.
First, it stresses that it will not know the impact of lockdown measures for some time, that it is too soon to understand the impact of releasing them, and there is high risk of failure: ‘There is a danger that lifting measures too early could cause a second wave of exponential epidemic growth – requiring measures to be re-imposed’ (2.4.20: 1; see also 14.4.20: 1-2). This problem remains even if a reliable testing and contact tracing system is in place, and if there are environmental improvements to reduce transmission (by keeping people apart).
Second, it notes signals from multiple sources (including CO-CIN and the RCGP) on the higher risk of major illness and death among black people, the ongoing investigation of higher risk to ‘BAME’ health workers (16.4.20), and further (high priority) work on ‘ethnicity, deprivation, and mortality’ (21.4.20: 1) (see also: Race, ethnicity, and the social determinants of health).
Third, it highlights the need for a ‘national testing strategy’ to cover NHS patients, staff, an epidemiological survey, and the community (2.4.20). The need for far more testing is a feature of almost every meeting (see also The need to ramp up testing).
Fourth, SAGE describes the need for more short and long-term research, identifying nosocomial infection as a short term priority, and long term priorities in areas such as the long term health impacts of COVID-19 (including socioeconomic impacts on physical and mental health), community testing, and international work (31.3.20: 1-2).
Finally, it reflects shifting advice on the precautionary use of face masks. Previously, advisory bodies emphasized limited evidence of a clear benefit to the wearer, and worried that public mask use would reduce the supply to healthcare professionals and generate a false sense of security (compare with this Greenhalgh et al article on the precautionary principle, the subsequent debate, and work by the Royal Society). Even by April: ‘NERVTAG concluded that the increased use of masks would have minimal effect’ on general population infection (7.4.20: 1), while the WHO described limited evidence that facemasks are beneficial for community use (9.4.20). Still, general face mask use but could have small positive effect, particularly in ‘enclosed environments with poor ventilation, and around vulnerable people’ (14.4.20: 2) and ‘on balance, there is enough evidence to support recommendation of community use of cloth face masks, for short periods in enclosed spaces where social distancing is not possible’ (partly because people can be infectious with no symptoms), as long as people know that it is no substitute for social distancing and handwashing (21.4.20)
In May, SAGE continues to discuss high uncertainty on relaxing lockdown measures, the details of testing systems, and the need for research.
Generally, it advises that relaxations should not happen before there is more understanding of transmission in hospitals and care homes, and ‘until effective outbreak surveillance and test and trace systems are up and running’ (14.5.20). It advises specifically ‘against reopening personal care services, as they typically rely on highly connected workers who may accelerate transmission’ (5.5.20: 3) and warns against the too-quick introduction of social bubbles. Relaxation runs the risk of diminishing public adherence to social distancing, and to overwhelm any contact tracing system put in place:
‘SAGE participants reaffirmed their recent advice that numbers of Covid-19 cases remain high (around 10,000 cases per day with wide confidence intervals); that R is 0.7-0.9 and could be very close to 1 in places across the UK; and that there is very little room for manoeuvre especially before a test, trace and isolate system is up and running effectively. It is not yet possible to assess the effect of the first set of changes which were made on easing restrictions to lockdown’ (28.5.20: 3).
It recommends extensive testing in hospitals and care homes (12.5.20: 3) and ‘remains of the view that a monitoring and test, trace & isolate system needs to be put in place’ (12.5.20: 1)
In June, SAGE identifies the importance of clusters of infection (super-spreading events) and the importance of a contact tracing system that focuses on clusters (rather than simply individuals) (11.6.20: 3). It reaffirms the value of a 2-metre distance rule. It also notes that the research on immunology remains unclear, which makes immunity passports a bad idea (4.6.20).
It describes the result of multiple meeting papers on the unequal impact of COVID-19:
‘There is an increased risk from Covid-19 to BAME groups, which should be urgently investigated through social science research and biomedical research, and mitigated by policy makers’ … ‘SAGE also noted the importance of involving BAME groups in framing research questions, participating in research projects, sharing findings and implementing recommendations’ (4.6.20: 1-3)
See also: Race, ethnicity, and the social determinants of health
The full list of SAGE posts:
COVID-19 policy in the UK: yes, the UK Government did ‘follow the science’
Did the UK Government ‘follow the science’? Reflections on SAGE meetings
The role of SAGE and science advice to government
The overall narrative underpinning SAGE advice and UK government policy
SAGE meetings from January-June 2020
SAGE Theme 1. The language of intervention
SAGE Theme 2. Limited capacity for testing, forecasting, and challenging assumptions
SAGE Theme 3. Communicating to the public
COVID-19 policy in the UK: Table 2: Summary of SAGE minutes, January-June 2020