Professor Derek Ward urged people to stay inside this week, whether they show symptoms or not.
It comes as the government’s chief scientific advisor Sir Patrick Vallance warned that deaths from COVID-19 will get worse and the country should stay in lockdown until the virus stabilises.
Professor Ward said this week in particular will be “really important” for the county’s response to the virus.
“If people did catch the virus at the beginning of last week, they will start to become symptomatic,” he said.
“If people stay in, whether they are symptomatic or not, if they can stay in and stay away from others they will kill it and stop the spread.”
Professor Ward added that it was important for people to look after their mental health while in isolation, including creating a routine and having conversations with others.
More information on how people can look after their mental wellbeing can be found on the NHS website.
So far, nine patients who tested positive for COVID-19 have died in Greater Lincolnshire.
Six have been recorded in Lincolnshire, while three have died in northern Lincolnshire hospitals.
Professor Ward said, however, he expects the figures to increase in the coming weeks.
Meanwhile, 113 positive cases of coronavirus have been confirmed in Greater Lincolnshire.
78 in Lincolnshire
20 in North East Lincolnshire
15 in North Lincolnshire
Across the UK, the figures stand at 22,141 confirmed COVID-19 cases and 1,415 deaths.