BERLIN (BLOOMBERG) - German Chancellor Angela Merkel broke down the maths behind the spread of the coronavirus in a delightfully nerdy, yet simple explanation that is earning her praise for her clarity.

Germany is now at the point where each person with the virus infects an average of one other person, Dr Merkel said on Wednesday (April 15) at a briefing in Berlin. If each person infects just 1.2 other people, what seems like a tiny increase will have big repercussions and put the healthcare system at maximum capacity by July, she said.

Breaking down the numbers is par for the course for the German Chancellor, who has a doctorate in physical chemistry. The reproduction factor she described - known by epidemiologists as R0, pronounced R-nought - is a key metric for how successful countries have been at keeping the epidemic in check.

"You can see what a tight margin we're working with," Dr Merkel said, noting that a reproduction factor of 1.2 means that one in five coronavirus patients infects two others, instead of only a single other person.

"This is thin ice," she added. "Really a situation in which caution is the order of the day and not foolhardiness."

In Germany, R0 currently stands at 0.9, the country's public health authority, the Robert Koch Institute, said late on Wednesday.

Dr Merkel unveiled plans for a gradual return to normalcy after three and a half weeks of lockdown to halt the spread of the virus. Germany will allow some smaller shops to reopen next week and move toward reopening schools in early May.