French GDP would have declined by 6% in the first quarter according to the Banque de France. It is the first estimate of the 1st quarter of 2020 in developed countries. Over the whole year, the decline in GDP could be at least 10 to 15%

The Banque de France announced a -6% drop in French GDP in the first quarter. This makes a carry over growth for 2020 at -5.8% at the end of the first quarter (change in activity for the whole 2020 if the level of GDP remained at the first quarter level for the last three quarters).
GDP level is back to mid-2015 level. The time of containment has erased more than 4 years of growth. For the whole year, GDP could fall between 10 and 15% may be more. The risk is on the downside.

The Banque de France indicates that in the industry, the number of days of exceptional closure was only 5 on average for a lockdown period of 10.5 days (excluding weekends). In services this figure is 6 days on average.
The loss of activity in March would be 17% taking into account the two weeks of lockdown.
Therefore if the whole of April is in containment, as the Prime Minister suggests, the decline in additional activity will be greater because it is applied to the whole of the month. The Banque de France indicates in its note that two weeks of confinement removes 1.5% of annual growth. This would translate into 3% less in 2020 if the whole of April is confined. The gain at the end of April for 2020 GDP would therefore be -9%.

For the following, the question arises of the possibility of leaving containment. Whatever the scenario, we cannot assume a return to normal and a return to the previous trend during 2020.
To recover a stronger momentum on activity, then it is necessary to exit from the lockdown, sectors that have been the most penalized, in particular in industry.
In the Banque de France survey, the transport, metallurgy and capital goods sectors should be favored in industry. In services, the sectors most affected are those penalized by respect for social distancing (accommodation, catering, car repair or temporary work and trade). The least affected services are those intended for businesses.
The exit from the lockdown can not take place at once and for everyone, then we must assume that the GDP will continue to contract in May and June, probably on a less significant basis than the 3% per month associated to complete containment.
For the next two quarters, activity could stabilize at best. Consequently, over the whole year, GDP could fall by at least 10 to 15% compared to 2019.