A study recently published by Imperial College London estimates measures implemented to slow the spread of the SARS-CoV-2 virus might have saved 3.1 million lives across 11 European nations, including Switzerland.
From 2 to 29 March 2020, European countries began implementing measures to slow viral transmission, such as school closures and national lockdowns, to control the COVID-19 epidemic.
The focus of the study was modelling the reproduction number (R), which is the number of people each infected person infects.
Instead of case numbers the Imperial team used death data to infer changes in the course of the COVID-19 epidemic. They analysed data up until 4 May 2020 from 11 countries in Europe, including the United Kingdom, Spain, Italy, Germany, France, Switzerland, Sweden, Denmark, Norway, Austria and Belgium.
Their modelling estimates that between 12 and 15 million individuals in these countries had been infected with SARS-CoV-2 by the beginning of May. These figures translated to 3.2% to 4% of the population, depending on the country. These percentages are in line with other studies, such as the large antibody test programme in Spain published in mid May, which estimated an infection rate of around 5% in Spain.
By comparing the number of observed deaths against those predicted by their model in the absence of interventions, the authors estimate that around 3.1 million deaths have been averted due to the non-pharmaceutical measures implemented.
They calculate that the reproduction number has dropped to below one as a result of the interventions, decreasing by an average of 82%, although the values vary from country to country.
The model implies infection fatality rates (IFR) of between 1.26% (France) and 0.91% (Norway) if nothing was done to reduce spread. The implied IFR for Switzerland was 1.02%
Sweden versus Switzerland
In Switzerland, the model estimates spread reduction measures took the reproduction number from around 3.2 to around 0.5 (-2.7). In Sweden, the reproduction number went from around 2.7 to around 0.7 (-2.0).
These numbers suggest Sweden started with a natural advantage (2.7 vs 3.2) and its measures had less effect. Switzerland brought its reproduction rate down by -2.7 compared to -2.0 in Sweden.
Both nations closed schools. However, Sweden only closed colleges and upper secondary schools on 18 March 2020. Switzerland closed all schools on 14 March 2020.
Both countries banned events, but Switzerland was more restrictive than Sweden. Switzerland banned gatherings of >100 people on 13 March and gatherings of >5 on 20 March. Sweden only banned gatherings of >500 on 12 March.
Switzerland went further with social distancing too. In Sweden people were encouraged to social distance and work from home. In Switzerland, non-essential businesses where social distancing is difficult were forced to close. In Sweden, they stayed open and operated with social distancing and fewer customers.
By 12 June 2020, Sweden had recorded 481 Covid-19 deaths per million and had rising new daily infections of around 800 on a 7-day rolling average basis. By the same date, Switzerland had recorded 224 deaths per million and new daily infections were running at around 20 on a 7-day rolling average basis. Sweden’s new daily infection numbers were about 35 times higher than Switzerland’s on a per capita basis.
The authors of the Imperial study caution the interpretation of the results. One limitation is that the model assumes that each measure had the same effect on all countries, whereas in reality, there was variation in how various measure were implemented in different countries.
However, the authors conclude that lockdown has a substantial effect in reducing the reproductive number below one and had helped to contain the spread of COVID-19 by the beginning of May 2020, possibly saving 3.1 million lives.
The 11 countries included in the study have a combined population of around 374 million and had recorded a total of around 160,000 Covid-19 deaths by 12 June 2020.
Studies such as this one that aim to quantify the effects of anti-spread measures have the potential to spark criticism of decision makers.
Prosecutors in Italy have questioned the Italian prime minister about aspects of his response to the pandemic. Some claim delays in locking down the northern Italian towns of Alzano and Nembro caused the virus to spread in the badly hit region of Lombardy.
More on this:
Imperial College London study (in English)
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