IMAGENS DE OVOODOCORVO
I’m an
epidemiologist. When I heard about Britain’s ‘herd immunity’ coronavirus plan,
I thought it was satire
William
Hanage
Vulnerable
people should not be exposed to Covid-19 right now in the service of a
hypothetical future
Sun 15 Mar
2020 12.33 GMTLast modified on Sun 15 Mar 2020 13.29 GMT
Your house
is on fire, and the people whom you have trusted with your care are not trying
to put it out. Even though they knew it was coming, and could see what happened
to the neighbours as they were overwhelmed with terrifying speed, the UK
government has inexplicably chosen to encourage the flames, in the misguided
notion that somehow they will be able to control them.
When I
first heard about this, I could not believe it. I research and teach the
evolution and epidemiology of infectious disease at Harvard’s Chan School of
Public Health. My colleagues here in the US, even as they are reeling from the
stumbling response of the Donald Trump administration to the crisis, assumed
that reports of the UK policy were satire – an example of the wry humour for
which the country is famed. But they are all too real.
Let me take
the arguments on their merits. The stated aim has been to achieve “herd
immunity” in order to manage the outbreak and prevent a catastrophic “second
wave” next winter – even if Matt Hancock has tried to put that particular genie
back in the bottle this weekend. A large proportion of the population is at
lower risk of developing severe disease: roughly speaking anyone up to the age
of 40. So the reasoning goes that even though in a perfect world we’d not want
anyone to take the risk of infection, generating immunity in younger people is
a way of protecting the population as a whole.
We talk
about vaccines generating herd immunity, so why is this different? Because this
is not a vaccine. This is an actual pandemic that will make a very large number
of people sick, and some of them will die. Even though the mortality rate is
likely quite low, a small fraction of a very large number is still a large
number. And the mortality rate will climb when the NHS is overwhelmed. This
would be expected to happen, even if we make the generous assumption that the
government were entirely successful in restricting the virus to the low-risk
population, at the peak of the outbreak the numbers requiring critical care
would be greater than the number of beds available. This is made worse by the
fact that people who are badly ill tend to remain so for a long time, which
increases the burden.
And of
course you can’t restrict it to this age group. Think of all the people aged
between 20 and 40 who work in healthcare, or old people’s homes. You don’t need
many introductions into settings like these for what we might coyly call
“severe outcomes”. In Washington State, nearly all the deaths reported so far
have been associated with nursing homes. Is everyone in a high-risk group
supposed to withdraw themselves from society for six months until they can
emerge once the (so far entirely imaginary) second wave has been averted?
About that
second wave: let me be clear. Second waves are real things, and we have seen
them in flu pandemics. This is not a flu pandemic. Flu rules do not apply.
There might well be a second wave, I honestly don’t know. But vulnerable people
should not be exposed to a virus right now in the service of a hypothetical
future.
Keeping
people safe means self-isolation if you develop symptoms, but the official
advice here is also misleading. While it is of paramount importance that sick
people stay at home to avoid infecting others, it is increasingly clear that
transmission can occur before symptoms develop. We know this is true from
modelling and observational studies. I have seen it happen myself. We do not
know how often it occurs or how important it is in the epidemiology, but it
definitely does happen.
However,
arguments about the case fatality rate, the transmission parameters and
presymptomatic transmission all miss the point. This virus is capable of
shutting down countries. You should not want to be the next after Wuhan, Iran,
Italy or Spain. In those places, the healthcare systems have broken down. In
Italy, the choices of whom to save and whom to allow to die are real. You
should instead look to the example of South Korea, which, through a combination
of intense surveillance and social distancing, appears to have gained some
semblance of control over the virus. We can learn from South Korea, Singapore,
Hong Kong and Taiwan, all of which have so far done a good job mitigating the
worst outcomes despite having reported cases early in the pandemic, and in the
case of South Korea, suffering a substantial outbreak.
The UK
should not be trying to create herd immunity, that will take care of itself.
Policy should be directed at slowing the outbreak to a (more) manageable rate.
What this looks like is strong social distancing. Anyone who can work from home,
should. People who do not yet work from home should be encouraged to do so.
Employers should guarantee sick pay, including for contacts of known cases, and
do everything they can to discourage the practice of “presenteeism”. You should
not shake hands. Not with anyone. You should wash your hands for 20 seconds
several times a day and whenever you enter your home (or someone else’s home).
Call a halt to large gatherings. Educate people about masks and how they should
be reserved for the medical professionals who need them. All this and more
should have started weeks ago.
Deciding
whether to close schools is hard; they do so much more than just education. But
this is a pandemic, and so you should expect they will be shut sooner or later.
In Hong Kong, they have been shut for weeks. If you hear any talking head on TV
explain that kids don’t get sick, remember that doesn’t mean kids cannot be
infected and transmit. It’s probably a good idea to hold off on visits to Nana
and Grandpa.
The most
fundamental function of a government is to keep its people safe. It is from
this that it derives its authority, the confidence of the people and its
legitimacy. Nobody should be under the illusion that this is something that can
be dodged through somehow manipulating a virus that we are only beginning to
understand. This will not pass you by; this is not a tornado, it is a
hurricane.
Don’t
panic, but do prepare. If your government won’t help you, do it yourself.
• Dr
William Hanage is a professor of the evolution and epidemiology of infectious
disease at Harvard
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