Dr. Sakthi Karunanithi urged people with even mild symptoms to do the right thing and self-isolate. He also said those without any reason to believe they have Covid should nevertheless test themselves before meeting up with others.
His message comes as the latest figures show that case numbers more than doubled in most council areas in the week up to Christmas Eve, compared to the rolling weekly figure seven days earlier.
West Lancashire, Wyre and Chorley saw the biggest increases in Lancashire at 162, 137 and 134 percent respectively. In South Ribble, the figure was 117 percent, while Preston's increase stood at 92 percent.
Across Lancashire as a whole, there were 16,621 confirmed Covid cases in the week to 24th December - a case rate of 1,140 per 100,000 people.
South Ribble and Chorley have the highest such rates in the county - 1,422 and 1,409 respectively.
Dr Karunanithi, Lancashire County Council's director of public health, said: "As we welcome in the new year, we know people may want to celebrate with family, friends and loved ones.
“We are seeing a rapid increase in cases here in Lancashire and even a small percentage needing hospital treatment will add pressure on our local NHS services.
"There are a few simple steps people can take to help stop the spread. Take a lateral flow test before catching up with people, wear a mask where possible and remember your routine of hands, face, space and fresh air.
“If you have a temperature, cough, loss or change to your sense of smell or taste, or the new Omicron symptoms which include a runny nose, sore throat and a headache - no matter how mild - you need to isolate as quickly as possible. It is the right and safe thing to do.
“If you haven’t yet had your vaccination or booster, now is the time to book. There has already been a great uptake, and more appointments are available despite this still being the festive season," Dr. Karunanithi said.
LANCASHIRE'S COVID CASE COUNTS
Number of cases per council area in the week to 24th December, followed by the increase in that number compared to the rolling seven-day tally a week earlier.
Blackburn with Darwen - 1,428 cases (up 97.8%)
Blackpool - 1,204 cases (up 128.9%)
Burnley - 890 cases (up 130.6%)
Chorley - 1,675 cases (up 134.9%)
Fylde - 837 cases (up 96.5%)
Hyndburn - 784 cases - (up 92.2%)
Lancaster - 1,863 cases (up 117.1%)
Pendle - 723 cases (up 117.8%)
Preston - 1,544 cases (up 1071.1)
Ribble Valley - 811 cases (up 104.8%)
Rossendale - 854 cases (up 120.1%)
South Ribble - 1,580 cases (up 116.7%)
West Lancashire - 1,484 cases (up 162.2%)
Wyre - 944 cases (up 137.2%)