Rethinking flattening the curve(s) during Covid19

In March of this year, Covid19 started spreading rapidly in Europe. Schools and borders closed, and many people started working in home office. Initially, in Germany these closures and changes were announced to run until after Easter (for six weeks). The first shutdown period was then extended until the end of the school year (June).

Schools, borders and offices have since then reopened, but as autumn and the indoor-period has started, a second shutdown seems to be lurking around the corner, as infections are again rising rapidly and large proportions of the public are not fully adhering to public health guidelines (distancing, mask wearing, hygiene, reducing travel and social gatherings). As intensive care unit (ICU) beds are filling up fast, first closure measures have been announced (in Berlin for night-time hours), and we should expect further closures to follow – and be prepared for a second shutdown.

The problem with ‘flatting the curve’

One problem that I have previously flagged is that the public was told that the Covid19 curve could be flattened, and would then peter out. ‘Flatting the curve’ was all the rage during the spring to explain why infections had to stay at or below health care capacity (i.e. to ensure that the health system could care for sick people, in addition to all other health issues). It’s a great and clear explainer, with one caveat: It created the expectation that Covid19 cases would drop, then disappear – and never return.

We know that Covid19 has not gone away, and can easily return. And public health experts knew this already in spring, which makes the use of this curve visual quite perplexing. The problem was that this curve visual oversimplified what was happening, and did not explain what would happen later. The result was that the public was given the impression that this was a one-off situation, with a one-off loss of freedom, income, education, and social contacts.

Flatting the curveS?

Instead, health care capacity (for Covid19) has been increased in most countries, including Germany. In Berlin, an additional 500 to 1,000-bed ICU emergency unit was constructed, and additional emergency doctors and support staff were recruited (including already retired doctors, and medical students).

Politicians – and also some public health experts – have quite heatedly debated what this additional capacity and preparedness (including testing, tracing, isolation procedures) means for a renewed curve. Can the health system now handle more Covid19 cases, and life (and the economy, travel, education system, social gatherings, and travel) can return closer to “normal”? Or are even mild Covid19 infections dangerous, because they risk spreading to high-risk populations (resulting in severe cases and deaths), and because patients who have recovered from infections have been found to suffer from long-term complications? Also ethically, how many deaths are “acceptable”? (The case of Sweden is a good example for this debate.)

The current strategy still seems to be to try to ‘flatten the curve’ – or ‘curves’, as infections start spiking for a second or (in some countries) third time. The very rough-and-dirty graph below illustrates these two above trends: increased health care capacity, and several curves.

The graph shows two curves: one with an uncontrolled or mismanaged response, where infections keep spiking above what the health system can handle (i.e. likely resulting in high death rates). The lower curve is a managed response (i.e. ‘flattened’), which remains below health care capacity (well below when capacity is increased).

What the graph does not show – but ideally would – is that a flattened curve can also again spiral out of control – above health care capacity, and become uncontrolled. This critical point is something that the public should be made aware of, including their agency to counter this effect by adhering to public health guidance.


Public and global health expert Professor Devi Sridhar in July explained another strategy for Covid19 that moves away from ‘flatting the curve’ to focusing on ‘elimination‘ (i.e. getting to zero cases).

Here health care capacity may or may not be increased, but the aim is to keep Covid19 cases as low as possible, ideally keeping them at or as close to zero until a vaccine is made universally available.

But even here, a ‘renewed curves’ graph would be helpful to illustrate that getting to zero – but not yet having a vaccine – may mean that a new curve can develop, even an uncontrolled one.

What this means for public communication

‘Flatting the curve’ was a helpful illustration for the first wave of Covid19 cases, explaining why infections had to be reduced – or at least contained at manageable numbers.

With second or third waves coming up – or already spiking in many countries – it’s high time that health communicators and public campaigns on Covid19 explain what has changed since. Where are we on the curve? What is our goal? What action is needed? Is this a one-off, or are we in for the long game?

Right now the public is left in a vacuum of information in many countries. They are asking themselves why they should keep doing what they were doing before? Didn’t it help? Why do they need to restart? What’s the strategy? What’s the goal? What’s the timeline?

My suggestion is that ‘flattening the curve’ needs a rethink, and can become a powerful public health information tool again if used correctly. But it has to illustrate the situation in a way that does not oversimplify, and must take into account what happens next – and bring in agency.

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