COVID-19 Europe in Lock Down. Flatten-the-curve. But for how long, and will it flatten?
- Jeroen van Gennep
- Mar 16, 2020
- 8 min read
Now that we are going into a new phase of lock-down in Europe. Four key questions, critical to these far-reaching steps, arise:
1) For how long is the lock-down expected to last?
2) How effective is a lock-down?
3) Can asymptomatic carriers spread coronavirus?
4) How long do the antibodies remain in the people who have had the COVID-19 virus and recovered?
DISCLAIMER: I am not a medic, nor do I propagate to be and am open to stand corrected.
A very insightful article from the Washington Post about how to “flatten the curve” was published on March 14th.
The key graphs are:
The three colours:
Turquoise are uninfected people
Brown are infected people
Purple are recovered people
With moderate distancing (the 3rd graph from the left) being where 75% don’t move and are ‘social distancing’ (a vague, generalist, term I will come back to below). The 4th graph from the right goes even further and shows when 87.5% of the population don’t move and are taking social distancing measures in this model.
The key message this shows is that yes when less people move around, we do dampen and delay the curve. But the 4th graph also shows that the more we create a lock-down, the lower the proportion of people in the population who have had the virus and recovered, and hence have immunity due to the created antibodies. What the models do not show is: 1) What happens after social distancing/lock-down is slackened or even fully revoked? 2) How long the social distancing/lock-down are meant to last?
1) How long will the lock-down last? We could be talking up to a year and a half.
Martin Hibberd, professor of emerging infectious disease at the London School of Hygiene & Tropical Medicine states in the Guardian newspaper “Another strategy [opposed to herd immunity] might be to try to contain [it] longer and perhaps long enough for a therapy to emerge that might allow some kind of treatment. This seems to be the strategy of countries such as Singapore. While this containment approach is clearly difficult (and may be impossible for many countries), it does seem a worthy goal; and those countries that can should aim to do.”
While Melanie Saville, director of vaccine research and development at CEPI states on Science|Business“that there are no guarantees of delivering a vaccine, the “aspiration” is to have millions of doses available for public use within 12 to 18 months – “a very accelerated timeline,”. The Cepi was set up in response to the lack of scientific progress when Ebola ripped through West Africa in 2014 to 2016. Their existence is a huge boost for vaccine research. Cepi's mission is to rapidly respond to epidemics by providing the money to researchers to develop vaccines.
So even in the most ambitious cases it will be a year to a year-and-a-half till a vaccine is available. Do we lock-down until then? In the UK there are already plans to inform all over-70s to self-isolate for several months as reported in The Independent newspaper.
To come back to the terms of social distancing/self-isolation/quarantine. Another widely shared graph is the following:
Which defines proactive measures as “social distancing such as teleworking, limiting large gatherings, reducing travel or more assertive approaches”. I also regard the no handshaking, kissing or hugging as forms of social distancing. While regular and thorough handwashing, coughing and sneezing in one’s elbow can be defined as increased personal hygiene.
(Self-) isolation and quarantine also fall into social distancing. But I will take the definition as defined here that quarantine is for people who are not currently sick, but have been or may have been exposed to a communicable disease. Isolation happens when a person is infected with a communicable disease and is separated from people who are healthy.
The current lock-down, with no travel, working from home, no social contacts are forms of social distancing that is in part isolation as there are people infected with COVID-19 and at the same time a form of quarantine as there are also many people who are not infected.
The article in the Washington Post states that the models are when people “don’t move” and are “social distancing”. But essentially in those models it comes down to a lockdown with 75% to 87.5% of the population in isolation (the term for people with the virus) and quarantine (the term for people without the virus) without an indication at all of the duration to keep them there.
The key questions will be what degree of social distancing will be the most effective, do we require isolation of those with the symptoms, quarantine also for the healthy or should we aim for some form of controlled introduction to the virus? Further, we must question if a lock-down is enforceable for weeks, perhaps months, or even year(s)? What would the negative externalities be of such a lock-down, not only to the macro-economy but also people’s physical and mental health and ability to provide for themselves and their family?
2) How effective is a lock-down?
Let’s go back to this graph:
Where red is if we allow uncontrolled transmission, green would be the ideal flattening of the curve and no new cases arrive due to protective measures.
If we have a full, or too effective, lock-down we run the risk of simply increasing the curve once the lock-down is revoked making the number of cases peak after it is revoked as shown below:
What we should perhaps rather strive for would be a curve that looks like this:
Where the blue curves show when as soon as the number of cases decrease there is a rise of new cases. This could already be happening while social distancing is invoked, as there is not a 100% prevention of interaction, not even in the models as simulated by the Washington Post. The coming days and weeks will tell.
But, it maybe that this is happening too slowly or not effective enough and what is required to ensure that there is herd/group immunity is a controlled infection of parts of the population to COVID-19. It will be very difficult to know beforehand what the actual results will be and I think we should be clear that there are risks with both strategies, strategy A) prevent as many people as possible getting the virus and strategy B) at some point allow controlled infection of parts of the population. The risk with strategy A is that the peak will increase later-on, with strategy B the risk is that we cannot manage the number of new cases well-enough. With both strategies there will be cases where people require hospital-care and in both strategies there will be people who die as a result of the virus. The long-term course should be the preservation of life and keeping people safe, the question is which strategy does that best.
It could also be that the answer is a hybrid of the two strategies, all those who are considered at risk (the elderly and those with pre-existing health conditions) stay in protective quarantine while at different stages different groups of the population are exposed to COVID-19. This could be based on their location so one part of a country can be prepared for a new increase in the curve of cases or on some other criteria.
A final point we must not forget is that hospitals and other health-care institutions are taking extraordinary measures to increase their capacity. So it could also be that as health-care capacity increases that the course that is the most risk-averse (taking as a given that we cannot eradicate the COVID-19 virus) would be to, over time, increase the amount of new cases, shown in the graph below, with the hope that by doing so we dampen any potential peak in the fall/winter when health-care systems will again be under strain due to the seasonal increase in care required due to the other endemic viruses we already have.
3) Can asymptomatic carriers spread coronavirus?
See my post of March 13th regarding the (flawed) primary research on which a lot of media outlets are basing the fact that a (large) percentage of infections happen via asymptomatic carriers.
I am neither an expert nor a medic but from the many primary and secondary sources do believe that if there is a chance to be infected by someone who is asymptomatic the chances are much much lower than someone who does show symptoms. But at the present time, like with most things regarding COVID-19 it is too early to fully tell.
4) How long do the antibodies remain in the individuals who have had the COVID-19 virus and recovered?
This will be critical to the strategies of all health authorities and governments. People who have had and recover from COVID-19 will have created antibodies. As long as these antibodies are present the individual will not catch the same strand of COVID-19 again and cannot infect others. This would mean also slowing the spread to those in the population who do not have the antibodies. Even if the threshold of 60-70% is not met to have a fully functioning herd immunity (that effectively the virus cannot spread through the population), every additional person with the antibodies will slow the further spread.
Francois Balloux (twitter @BallouxFrancois) states, “How long immunity lasts for following covid-19 infection is the biggest unknown. Comparison with other Coronaviridae suggests it may be relatively short-lived (i.e. months). If this were to be confirmed, it would add to the challenge of managing the pandemic.” Francois Balloux’s is in his own words a computational/system biologist working on infectious diseases and has spent five years in a world class 'pandemic response modelling' unit. But Balloux fails to share the source for the suggestion that the immunity is short lived and I have been unbale to find any primary papers examining this. Again, at the present time, like with most things regarding COVID-19 it is too early to fully tell.
In conclusion if we (have to) accept that we cannot stamp the virus out, that it will take more than a year for a vaccine to be readily available, that people who show no symptoms cannot, or at least at a much lower rate, spread the COVID-19 virus and that there is at least some immunity in people who recovered, should we not (re)discuss the options between a full-lock down and other social distancing strategies that cause less negative externalities?
Or at least better explain how a lock-down now will not simply cause a peak later on, down the time axis, when the lock-down is revoked, with the virus still among us and we do not have enough people in the population with antibodies and no readily available vaccine? I understand a lock-down will delay the peak, potentially giving hospitals enough time to prepare but I fail to see how a lock-down of and by itself will dampen the peak.
To close, continue to make positive actions in the form of social distancing that have little to no negative externalities such as no handshaking, hugging, keeping 1.5-meter distance from others. Heighten your personal hygiene: washing your hands frequently for 20-30 seconds with soap, coughing and sneezing into one’s elbow. If showing symptoms self-isolate and in what now has become essentially a quarantine lock-down: stay at home as much as possible. But do not underestimate the impact this has, especially on those most vulnerable. If we continue to be in lock-down for weeks or perhaps even months, it will have an unprecedented effect on the economy.
But what is the economy if not in its most basic form the demand and supply of products and services, responsible for people’s jobs and the main source of income to support them in their livelihoods. Secondly, what will the effect be on people’s physical health, their mental health? People reliant on physiotherapy, or more critical reliant on medicine and other people for support. A lock-down cannot go on indefinitely and one has to question can it truly dampen ‘the curve’ or is it only flattened for the duration of the lock-down, simply to spike thereafter.
DISCLAIMER: I am not a medic, nor do I propagate to be and am open to stand corrected.
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