In all parts of the world, people are facing new and uncertain realities due to the coronavirus. In your business correspondence, especially emails, it's okay to say something about the current situation.
After an email greeting (such as "Dear Peter,"), you could write a sentence such as "I hope you and your family are well." A less formal alternative is "I hope you and your family are doing okay." If you know the person well, you could also ask "How are you and your family doing with the current situation?"
In sum, it's fine to say something about the situation before getting down to business. In fact, at the moment most people probably expect it.
Adding a personal touch to your emails can help to build a stronger business relationship, no matter what is going on in the world.