The government has
now said it will begin to wind down the lockdown with an extensive
test, trace and isolate (TTI) regime in place. Containment, having been
abandoned on March 12th, is back but this time the UK government is
serious about it. It has a much greater chance of success not just
because there is more testing capability available, and there will be
an app to help with tracing, but also because it will take place with
a degree of social distancing.
We can only hope
that this works, and that government actions match their words. But
what seems very puzzling to me is why the scientists advising the
government seem to have been preoccupied with moderated herd immunity
as the only way to deal with this virus, and largely neglected the
possibility that containment could be made to work.
Managed herd
immunity plus behavioural worries
This is not just a
UK issue. Herd immunity, together with limited and advisory social
distancing, is the strategy that is being tried in Sweden, following
the advice of their chief epidemiologist. It is controversial there
too, with many other scientists arguing against this strategy, and
with deaths in Sweden well above those in other Nordic countries.
The logic of the
argument for herd immunity is set out in a very interesting debate
on Channel 4 on 13th March. It was between John Edmunds, an
epidemiologist and member of SAGE, and Tomas Pueyo. (Although I saw
this at the time, thanks to @cubic_logic
for reminding me of it.) Both seem to agree that a lockdown of some
sort is required to avoid the health service being overwhelmed, with
the disagreement being how quickly that is required, but at the end
it seems both are in agreement about the principle of herd immunity.
Why not impose a
lockdown until a vaccine is discovered. You can also achieve herd
immunity with a vaccine, without hundreds of thousands of people
dying. If there was no cost to a lockdown, and it could be
successfully imposed for a year or more, the optimal strategy is
clearly to impose the lockdown as quickly as possible and retain it
until the vaccine arrives. Obviously a lockdown of that length would
be very costly, but the reason Edmunds gives in this debate for not
doing this is that people would stop observing it. This is the
‘behavioural’ element to the story that has been talked about.
The behavioural
element is crucial for the following reason. Even if it is not
successful, containment could allow the following strategy. You start
with containment (as we did), switch to total lockdown when
containment is obviously failing, and once that lockdown brings the
number of cases right down abandon it and revert to containment. This
on/off for the economy could get us to the point where a vaccine is
produced in large quantities. Compared to herd immunity we would
almost certainly cause far less deaths without too greater economic
cost.
To reject this
outcome requires a pretty firm belief that people would become so
tired of lockdowns by the Autumn that whatever the government did
there would be an uncontrolled epidemic in the winter with a worse
outcome for the NHS than managed herd immunity could achieve. Where
that belief comes from I don’t know, and neither will we know until
after the pandemic ends because the government has refused to publish
the scientific advice it received until then. You would think that
this behavioural assumption would depend in part on the economic
support individuals were receiving, but as far as I know no Treasury
officials or other economists were involved. Equally no sociologists
were involved.
It is here that
politics and science interact. Speaking to reuters’ journalists,
John Edmunds is reported
to have said:
“We had milder interventions in place because no one thought it would be acceptable politically to shut the country down.” He added: “We didn’t model it because it didn’t seem to be on the agenda. And Imperial didn’t look at it either.”
This is dangerous
territory for any scientist. In the blink of an eye a scientist
believing something is not on the agenda can be a politician saying
that no one told us about this alternative.
Once those advising
the government believed that lockdowns were off the agenda or too
fragile because of the behavioural response then the government’s
strategy begins to make more sense. You try containment, because
containment would be the best outcome, but you suspect that without
some social distancing and other measures it is unlikely to work, but
you don’t want to impose those for behavioural reasons. You then
move to managed herd immunity, where you want to impose as little
restrictions as you can get away with, again for behavioural reasons,
such that the NHS stays above the water line.
The strategy in
action
On 9th March, during
the containment phase, according to reuters:
“Johnson held out against stringent measures, saying he was following the advice of the government’s scientists. He asserted on March 9: “We are doing everything we can to combat this outbreak, based on the very latest scientific and medical advice.” Indeed, the government’s Scientific Advisory Group for Emergencies, SAGE, had recommended that day, with no dissension recorded in its summary, that the UK reject a China-style lockdown. SAGE decided that “implementing a subset of measures would be ideal,” according to a record of its conclusions. Tougher measures could create a “large second epidemic wave once the measures were lifted,” SAGE said.”
Whether this was a
unanimous view is disputed by Lawrence Freedman, who says
some members did favour something closer to a Wuhan lockdown.
Thus on 10-13th
March the Cheltenham racing festival went ahead. There is now
evidence
of a concentration of COVID cases in the area of Cheltenham
racecourse. Other sporting events were allowed to go ahead. While
this seems negligent if your concern is reducing deaths, if you think
herd immunity is the only option and you want to delay even a partial
lockdown for as long as possible it makes sense. On 12th March
containment ended, and in his first COVID press conference the PM
said “many more families will lose loved ones before their time.”
Testing is now limited to hospitals.
Yet at the same time
the Imperial team produced a new analysis suggesting that further
measures were needed to avoid overwhelming the NHS. This was ‘the
science changing’ according to the BBC. In reality this was still
the strategy of managed herd immunity. Freedman reports:
“Now, promoted by the Imperial study, the advice from the operations subgroup of the Scientific Pandemic Influenza group on Modelling (SPI-M-O) on 16 March was notably different in tone from a week earlier. The measures at first envisaged – case-by-case isolation, household isolation and social distancing of vulnerable groups – was now “unlikely to prevent critical care facilities being overwhelmed”. Everything now had to be tried, including “general social distancing and school closures”, which offered the best chance of disease control.”
But was this really
just the science changing? The reuters article says:
“What allowed Britain to alter course, said Edmunds, was a lockdown in Italy that “opened up the policy space” coupled with new data. First came a paper by Edmunds’ own London School team that examined intermittent lockdowns, sent to the modelling committee on March 11 and validated by Edinburgh University. Ferguson’s revised Imperial research followed. Woolhouse, the Edinburgh professor, confirmed the sequence. Edmunds said these new studies together had demonstrated that if the British government imposed a lengthy period of tougher measures, perhaps relaxed periodically, then the size of the epidemic could be substantially reduced.”
What changed was the
politics, which had “opened up” the alternative strategy of
intermittent lockdowns that I described at the beginning of this
post. It was inevitable that the politics would change. I noted
before Chris Giles commenting
that the herd immunity strategy was time inconsistent: once deaths
started increasing and people saw the pandemic overwhelming other
countries politicians were bound to change strategy. But Johnson
remained very reluctant to do so. As an article in the New England
Journal of Medicine says
about the measures introduced on 16th March:
“People should work from home if possible, but that was largely up to employers to decide. Vague. Anyone over 70 was advised to avoid “nonessential social contact.” Vague again. The government was “moving emphatically away from” mass gatherings, but again these were still not (and are still not) banned. British understatement was in full swing — citizens, businesses, and nursing homes were asked to read between the lines and go beyond explicit government policy. The prime minister’s father announced that he would be going to the pub if he chose to, since they needed the customers.”
We had to wait until
23rd March for the current lockdown to be imposed, that replaced
advice with something much stronger. The French President threatened
to close its borders with the UK if this was not done. As I noted in
last week’s blog post, the 10 days delay between the containment
phase ending and full lockdown probably cost the majority of lives
lost in the UK. I don’t think the difference between weak advice
(16th March) and the currrent lockdown (23rd March) can be pinned on
the scientists.
What mistakes did
scientists make
How much of all this the
fault of the scientists advising the government. They certainly made
mistakes. Three stand out. The first was NERVTAG
keeping the threat level at moderate in
mid-February, with Edmunds the only one objecting. This failed to
convey the urgency of the situation to the government. The second,
mentioned above, was scientists sticking to an agenda that seemed to
rule out a lockdown, or other scientists pretending they knew with
any certainty that lockdowns could not be sustained for long.
Cummings taking part in the meeting didn’t help here. People who
say his presence had no impact on the other people in the room, when
his actions could potentially hurt many of those people, have no
imagination.
The third, and by
far the most important, was the failure to realise that containment
if taken seriously was an alternative to herd immunity or total
lockdowns. East Asian countries like South Korea suggest that
alternative, if done properly and with supporting measures, can work
for some time. You test people who may have the virus, and if they do
you trace their contacts over the period they have been infectious
and isolate both them and their contacts. The South Korean experience
suggests that you can even bring down very high numbers of cases
using this strategy. Professor Ferguson now agrees
this is the country to learn from.
As long as a vaccine
comes along within two years, this is a strategy that can get you
through the period with no vaccine with far less cases and deaths
than with herd immunity. This option comes up in the Channel 4
discussion noted above, but Edmunds dismisses it as having been tried
and failed in the UK. In the UK this phase failed to stop the number
of daily cases increasing.
One of the lessons
from the countries with successful TTI strategies is that you close
down travel from infected areas very quickly, or impose compulsory
isolation for incoming travellers. (One of those countries, Taiwan,
has an epidemiologist as its deputy President,
which just shows that not all epidemiologists, or even a majority?
believe in herd immunity.) The UK failed to do this during our
containment phase. In addition, having mobile phone based tracing
apps is extremely helpful in tracing who people have been in contact
with, and the UK did not have that during its containment phase. But
more generally, mild forms of social distancing can be used to help
TTI work. Stopping large gatherings like Cheltenham races is an
obvious example. We can put the same point another way. The UK did
nothing to help the containment phase work. Was this due to politics
or the absence of advice from SAGE?
If TTI fails, as it
has in Singapore for example, then governments quickly need to impose
a lockdown. But this is not a reversion to a herd immunity strategy,
but just a measure required to get cases back down to a level where
TTI can work again. Even if TTI has to be accompanied by occasional
lockdowns, it will still involve many less deaths than herd immunity
or ‘running the NHS hot’ does, simply because of the mathematics.
Do these failures by
scientists advising the government, if they were not politically
influenced, get politicians off the hook? Absolutely not. Most
politicians, on being advised that the only sure way of responding to
a new virus was to let hundreds of thousands of people die (as they
were told in the UK), would surely want to be absolutely sure that
there really wasn’t any alternative. They would ask basic
questions, like are other countries doing the same, or are there
examples of countries that have chosen a different and less deadly approach.
Scientists would not have kept what China and South Korea are doing
from ministers, and they are unlikely to have said that these
countries' experience was of zero relevance.
If our government had done
that, I’m pretty sure we would have had containment with more
support in terms of controlling international travel, banning large
gatherings and so on. Herd immunity wouldn't have been on the agenda,
and a lockdown would have been imposed earlier. Probably most of
those who have died would still be with us. The reason we tried
containment in a half hearted way without social distancing support
or border controls were because politicians were too content with a
strategy that would kill huge numbers of people.
We are where we are
because our current Prime Minister and some in his cabinet, even in
the face of predictions of hundreds of thousands of deaths, was too
content
to do nothing, take
it on the chin, and too fearful of curtailing economic freedoms to
interrogate the advice they were given. It was the same slowness to
act, rather than anything coming from the scientists said, that led
to inadequate PPE provision, or to waiting until mid-March to appeal
for ventilators or make requests
to labs for assistance with testing.
What happens next
There
still seems to be divergent views within government about how quickly the lockdown
should be relaxed, where by relaxed I mean allowing more people to
get COVID-19. There shouldn't be any debate. The number of cases need
to be brought down as quickly as possible to a level where the TTI
regime can be pretty sure to work. The current lockdown has to
continue until that point is reached, and in addition some sort of
quarantine system has to operate on anyone coming into the country.
At
that point the TTI system can begin to operate. (Earlier testing should iron out any teething problems.) Only when this system has been operating for enough time to see that
it is clearly working can we begin to relax lockdown. But these
relaxations in lockdown need to be done step by step, and in each
case we need to ensure that TTI can still work successfully.