Belgium announces long-term models to handle pandemic

Belgium announces long-term models to handle pandemic
Credit: Belga

Belgium will handle the evolution of the pandemic based on several long-term models, announced Prime Minister Alexander De Croo during a press conference on Monday.

"As you know, there is a Consultative Committee on Friday and there are many questions to be asked about the current situation," said De Croo. "That is why we have asked experts to outline some scenarios of what could happen if we took certain measures, using different models."

"I would like to emphasise that no decisions will be made here," he said. "Decisions about the measures are political decisions, and they will be taken on Friday."

Current situation

"We had a very high second wave in October, but since then we have had a fairly stable period," said virologist and interfederal Covid-19 spokesperson Steven Van Gucht.

"That is not self-evident. Since November, we have had 2,000 to 2,500 infections per day. The fact that the curve is so flat is not the natural course of events," he said. "The measures serve as a counter-pressure, so the curve is flat."

6% of people with a confirmed infection end up in hospital, which means that 94% do not, Van Gucht explained. "The fact that it is not the case for 6% should not be minimised. Once the infection pressure rises, you will feel it in hospitals."

"In the intensive care units, we are seeing a long tail after the second wave. For the first time since November, we are seeing a slight increase again," he said.

"Nevertheless, Belgium is doing quite well. You can see that, among other things, when you look at the figures for the number of deaths," Van Gucht said. "If you compare Belgium to neighbouring countries, we had significantly fewer deaths at the beginning of January, and we are currently dealing with around 40 deaths per day."

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The measures in Belgium are also "relatively mild" compared to other countries, he said. "For some sectors they are harsh, but in general, there is much more freedom of movement than during the first wave."

"The consistency of the Belgian measures in recent months has, in my opinion, been a very strong asset," he said. "We have found a relatively good balance between the pressure of the virus and proportional measures, but it remains a fragile balance."

Additionally, the context has not really changed that much that making small changes to the measures is a smart idea, according to Van Gucht. "The situation is not fundamentally better than it was a month ago."

"In the future, however, that will probably change, as vaccination rates increase, spring is approaching with better weather, and within a few weeks we will have a much better idea of what the precise impact of the British variant will be on our figures and the effectiveness of our measures."

'Looking ahead'

"This is what the situation looks like today," said De Croo. "But we also want to look ahead."

"Mathematical models are not holy, that is very important to remember," said biostatistician Niel Hens. "They serve to make some of the epidemiological principles that have been put forward by my colleagues tangible."

"Therefore, it is sometimes wise not to look at those models too closely, because there is a very large source of uncertainty from all the information that we use in them."

"There are four scenarios, that I will explain. The models focus on hospital admissions, because that is one of the most important but also the most stable factors in this pandemic," Hens said.

The main uncertainty that remains concerns the advance and spread of the different variants of the virus. The different scenarios assume a higher infectivity of the variants: between 30% and 70%. The most likely scenario, however, is around 50%, according to him.

The first scenario assumes "stable contact behaviour" from 10 February, according to Hens. "This scenario assumes that the measures do not change," he said. "We might expect a flare-up, but that is a big uncertainty."

"The second scenario admittedly looks a lot more dramatic," said Hens. "In this scenario, we see a relaxation of the measures, or a return to the contact behaviour of the month of September, on 1 March. Remember that September was a month in which a lot was possible."

The third scenario shows what the curve would look like if Belgium started relaxing measures on 1 April. "Relaxing measures would already have a much more limited impact, because more people will have been vaccinated by then."

The fourth scenario illustrates what is likely to happen when the measures will be relaxed from 1 May. "In May, the same is true as in April, but even more so. A higher level of infectivity would then also remain manageable."

The idea of working with this kind of contact behaviour is to show, above all, how it affects the epidemic curve. "The reason we are not looking more closely is that there is still a lot of uncertainty about the British variant, and also to some extent the vaccination strategy as well," Hens said.

"We are facing a very important period, epidemiological speaking. We have to be patient. That is to say, we still have three to four weeks to wait and see what the impact of the British variant will be. What is also very clear is that there is perspective. All scenarios point very strongly to a decrease in the curve towards the summer holidays."

"I would like to add two nuances: firstly, we have not taken into account the seasonal effect, because the figures on this vary greatly."

"A second nuance is that the British variant probably leads to more hospitalisations and more mortality. We have not included that yet because the estimates on that vary widely. These are positive and negative elements that we have to take into account."

'Avoiding a third wave'

"We have heard very many voices in recent days, all asking for perspective," said De Croo. "And I think that is a very fair question."

"The measures we have in our country are very stable measures, as indicated, and that is something that helps. Of course, they are measures that we have had to bear for quite some time," he said.

"They are less strict compared to other countries, but that does not make them any less difficult to bear," De Croo said. "I absolutely understand everyone who is asking for perspective and something to look forward to. But we have to remain cautious, and avoid a third wave at all costs."

"But, we are approaching the point where the risk of a third wave seriously diminishes. Is that point tomorrow or next week? I think the presentations show not," he said. "But that point is also no longer very far away."

"If we give perspective, it should be based on facts and science. Perspective based on opinions is based on quicksand, and has little value," De Croo said. "It is up to the Consultative Committee on Friday to make the decisions. It is important, in my own view, that we base ourselves on scientific facts."

"We wanted to give some insight into the so-called engine room, so that it is a bit clearer to show how we arrive at certain decisions."

Maïthé Chini

The Brussels Times

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