The Department of Health said the transmission rate is currently very high, with one person in every 40 estimated to have the virus.
It comes as five further deaths of patients who had tested positive for Covid-19 were reported in Northern Ireland.
The Department of Health said there have also been 1,875 new confirmed cases in the last 24-hour reporting period.
On Friday morning there were 383 Covid-positive patients in hospital, with 45 in intensive care.
To help reduce transmission, the public are encouraged to spend as much time outside as possible and to increase ventilation when inside.
Sir Michael McBride said: “Covid-19 transmits best when people meet up indoors, particularly when there is poor ventilation.
“Make the most of the last days of summer and the best of the first days of autumn by meeting friends and family outdoors as much as possible. When inside remember to open windows to increase ventilation and reduce your risk of infection.”
Sir Michael also called on those not already vaccinated to get the jab as soon as possible.
He said: “Vaccination continues to be our most effective way of reducing transmission of the virus. If you’re not yet vaccinated please take the opportunity and go along to one of the pop-up vaccine clinics.
“It is vital that we remember the basics and keep following the public health advice. The advice remains – hands, face, space and let the fresh air in.
“Social distancing, face covering and hand washing all have a role to play in reducing transmission of this virus.
“Avoid busy and cramped indoor settings where ventilation is poor and if you have Covid symptoms, self-isolate and book a PCR test.
“Please continue doing all that you can to stop the spread infection”