Many trade contracts contain a clause that may protect trade contractors from catastrophic events like pandemics. These clauses are known as force-majeure clauses (covering acts of God). They basically say if these unavoidable events happen, the contractor is relieved of its obligations to the extent of the impact.
However, many common industry forms have not been updated to specifically address COVID-19. (They may be waiting to see how the courts treat their existing language first.) So to ensure impacts from COVID-19 are covered, a trade contractor should consider expressly adding it to the force-majeure clause. See the example below.
Notably, typical force-majeure clauses do not say the trade contractor gets more money. So an escalation clause could be added to the force-majeure clause.