POLITICO illustration Are the lockdowns working? Keeping people at home is slowing transmission of the virus, but policymakers face more uncomfortable choices.

Lockdowns in countries across Europe have been effective at reducing the coronavirus infection curve — but that leaves a tough dilemma for governments about what to do next.

Even with stringent measures still in place — notwithstanding moves by some countries to tentatively reduce confinement rules — the decline in daily cases is much less rapid than the initial exponential growth.

Now that countries have had several weeks under lockdown, with different measures adopted at different times, it is possible to see how effective they were. The picture is mixed.

As the chart shows, Italy, France, Germany and Spain progressively enforced the lockdown measures as the infection curve got steeper. The question for policymakers is: At what point is the decline strong enough to justify further easing of confinement measures?

To better compare countries, here is the data on a logarithmic scale along with the daily number of deaths from coronavirus. As expected, there is a lag between the infection curve peak and the peak in the numbers of deaths.

Some smaller European countries, such as Greece, Portugal, Czech Republic and Austria, appear to have dealt with their outbreaks more effectively by keeping the number of cases relatively low. Greece, for example, has recorded just 113 deaths from COVID-19. Even on a per capita basis, Spain has more than 40 times that amount.

What these countries did differently was to start the lockdown earlier than others, adopting measures more quickly than the other European countries, thus limiting the speed of the contagion. The benefit of that approach is particularly evident when the numbers are shown on a logarithmic scale (right-hand charts). Unlike in France, Spain, Italy and German, the numbers of new daily cases are now declining rapidly.

The situation in the U.K. is different, with the infection taking off later and confinement measures being put in place after most EU countries.

Analyzing the timing of the lockdown measures in different countries and the slowdown of the spread of the virus reveals a striking pattern. Using the doubling time of the outbreak in a country — the number of days it takes for confirmed coronavirus cases to double — we can get a further indication of how effectively countries were able to put a lid on the spread of the coronavirus. Remember, by this measure, a rising curve is a good thing because it means that the virus is spreading less efficiently, meaning that it takes longer for the number of cases to double.

Governments that banned nonessential internal movement before the third confirmed death from COVID-19 occurred saw the growth in the number of new coronavirus cases slow down two weeks later. The chart below highlights the developments in two countries with very different lockdown approaches. While the Czech Republic was among the first countries to ban nonessential movement, Sweden has introduced few restrictions.

Around the time of the third confirmed COVID-19 death in each country, doubling time is typically between one and six days. Two weeks later, the Czech Republic and Austria had already managed to slow down the spread of the virus and increase that time span to more than 10 days. At the same point, confirmed cases in France and the U.K. were still doubling every three to four days.

Sweden had a slower growth rate of cases at the start, but doubling time has increased significantly since — potentially a concern because it means the virus is still spreading relatively unchecked.

Here's the same graph but with the ability to pick out individual countries.

The take-home message for governments is that even once they pass the peak of infections they will need to be very careful in how they release confinement restrictions. Move too quickly and they risk a further spike in infections after a delay of a few days.

The lockdowns have been effective at slowing transmission of the virus, but without a vaccine or effectively treatment options, confinement is the only tool policymakers have.

This article is part of POLITICO’s premium policy service: Pro Health Care. From drug pricing, EMA, vaccines, pharma and more, our specialized journalists keep you on top of the topics driving the health care policy agenda. Email pro@politico.eu for a complimentary trial.