Current status: not yet any case law related to coronavirus, but legal principles

On 11 March 2020, WHO classified the coronavirus as a pandemic. On 22 March 2020, the Federal Government, in consultation with the Federal States, adopted a second package of measures which, in addition to the closure of various commercial enterprises and the prohibition of numerous services, in particular provides for a ban on contact for groups of more than 2 persons.
The effects of the coronavirus pandemic are manifold and are just beginning to be felt in the construction projects currently underway. Immediate effects include, in particular, the closure of buildings, increased levels of illness and quarantine among the contractor's employees, or inefficiency/obstructions due to the need to keep distances at the site. Indirect effects will include supply-chain bottlenecks and the absence of subcontractors due to entry bans.

The Federal Ministry of the Interior (Bundeinnenministerium) addresses some of these issues in its decree of 23 March 2020, which concludes that federal construction sites should continue as long as possible and reasonable. Furthermore, it is clarified that the coronavirus pandemic is in principle suitable to trigger the offence of force majeure within the meaning of Section 6 (2) No. 1 lit. c VOB/B (see also fig. 2 below). You can read the decree under the following link (in German):

The following discussions cannot draw on a case law developed for the current coronavirus pandemic. In view of the fact that the courts have suspended most of the proceedings, the development of coronavirus related case law is also not to be expected in foreseeable future. We therefore answer the questions arising in construction initially on the basis of the existing regulations in the VOB/B (German Construction Contract Procedures) and in the BGB (German Civil Code) and the decree of the BMI (Federal Ministry of the Interior) of 23 March 2020.