Relax? Not yet
Written on 18 April 2020, 07:45pm
My view on the recent study arguing that the lock-down measures implemented in Belgium should be relaxed to match the ones in the Netherlands, which lead to similar infection numbers. For completion, the 3 main differences between the two countries are:
- no legal enforcement of the lock-down in the NL
- all shops remain open in the NL
- telework is encouraged, but not mandatory in the NL
Note: For the sake of readability, I will add the relevant links at the end of the post.
What I liked in the study
- the dependency between the policy, human behavior and outcome
- the use of Google mobility data
The two premises
- I pretty much agree with the first one – about the complexity of the epidemic models and the fact that the Belgian government is not very transparent in sharing all the data. But we should not underestimate the importance of the scientists working together with the decision-makers.
- However, I do not agree with the second premise: that the models need precise data in order to work. Scientists routinely work with incomplete or imperfect data. Confidence intervals, margins of error, type I and II errors are all part of the game. This is not a perfect world.
- One of the problems stems from the first premise: we simply do not have all the data in order to make an objective judgement on the matter. Government, on the other hand, might do have the relevant data, and we have to accept that.
One of the most important variables is the reproduction number (R0) – which indicates of the infection is spreading or not. I am not aware of the Belgian authorities making this number public, but, despite the lack of widespread testing, that doesn’t mean they don’t have an idea how big R0 is.
Hypothesis: The R0 in Belgium is still over 1 with a confidence rate of 99%.
Question: Would it make sense to keep the current lock-down measures in place? I would answer yes, no matter how things are going in the neighboring countries.
- second, there are too many factors at play when comparing the situation in the two countries: the lock-down timing, the hospital capacity, the government risk appetite, the cultural differences between the two countries, the specific conditions of each country (ex. Brussels being a multi-cultural hub) or simply the luck. Trying to come up with a conclusive view while pandemic is still running its course is over-simplifying the whole context.
- third, comparing only two countries is bound to suffer from the small sample bias. The bigger view shows that lock-downs do work, and, more importantly, they might be more cost-efficient on the long run.
- The author probably doesn’t have much control on this, but some of the Belgian publications presented this study as a recommendation to suppress the lock-down measures, rather than ease them.
- The executive summary says: “Our goal is to determine, using a simple comparative method, the marginal utility of the most strict containment measures“. I am not sure this is the right approach in a study. The goal should be analyzing all the factors, and the utility of the measures could only be the conclusion, not the objective. Confirmation bias?
- From a visual point of view, it is highly recommended to harmonize the charts (different color schemes, different languages)
- Praising Sweden for reducing the R0 from 2.7 to 2 is a bit much. A transmission rate of 2 still means that each infected person transmits the virus to two other; or, in other words, exponential growth.
Relaxing the lock-down measures is “a very fragile” process. We currently don’t have the full picture to make a judgement, thus the comparison between two countries tends to over-simplify the context. I would trust the government in the decision-making process since it’s based on science and has more input data than we do. The precautionary principle is probably one of the factors at play, and the comparative utility of the containment measures should be only analyzed and judged when all this is over.
Update 19 April 2020
According to RTBF, the reproductive rate in Belgium is estimated at 0.8. A few comments on that:
– it’s a step in the right direction; the population has the right to know the evolution of R0 given all the inconveniences
– we’re talking about an estimation of the number, and there is no confidence interval (as in Hong Kong – see chart below)
– it is definitely good news that the R0 dropped below 1 and it shows that the lock-down measures worked
– however, this is not a sufficient reason to relax the measures. Context matters:
Each community must determine the real-time effective reproductive number it can accept given its own circumstances, in particular the stage of the epidemic it is at.https://www.nytimes.com/2020/04/06/opinion/coronavirus-end-social-distancing.html
Written by Dorin Moise (Published articles: 264)