'Act like you and everybody around you have Covid-19'.
That is the message from the assistant director of public health for Cornwall Council, Ruth Goldstein.
She told ITV News West Country there has been a "massive rise" in coronavirus cases in the county, which had previously seen the lowest rates in the country.
Parts of Cornwall have seen such a rapid increase in infection rates, they are now comparable with parts of London.
Dr Goldstein said Cornwall had been "really fortunate" before and during the Christmas break to experience low case rates, meaning it was under Tier 1 and 2 restrictions.
But that meant people were moving freely - and now cases are spreading rapidly.
Dr Goldstein said: “With the new variant, and with being in Tier 1 and 2, we were really in a position where people were able to move around more freely.
"It's not our overall numbers, it's the rate of increase that's of real concern for us in Cornwall.
"From having incredibly low numbers to having much more higher numbers in line with the rest of the country, we’re just coming in line with the rest of the country but we’re coming in line with them really, really quickly and that’s what’s so surprising.”
She said the lockdown is now "absolutely vital" for people living in Cornwall, adding: "We absolutely need Cornish residents to be complying to the letter of the law with the lockdown, no little breaches here and there - no ‘oh well it won’t matter if I do something’.
"It matters what every single one of us does and we need everybody to act as if they and everybody around them has Covid."