The rate at which coronavirus is spreading from person to person in Northern Ireland is rising, official data suggests.
The Department of Health estimates the current reproduction (R) number is between 1.2 and 2 - and likely to be about 1.6.
The R number represents the number of individuals who, on average, will be infected by a single person with Covid-19.
It must remain below one to stop the virus spreading exponentially.
The R number can vary daily, but has been on the rise. Last week it was estimated at between 0.8 and 1.8. At the end of July it was between 0.5 and 1.
The Department of Health said: "When community transmission of the virus is very low, R will show a high degree of volatility and be heavily influenced by small local clusters.
"It will therefore no longer be the most informative or important number for the purpose of policy decisions.
"In these circumstances, the number of positive tests per day is likely to be a more important parameter."
On Thursday eight new cases of Covid-19 were confirmed in Northern Ireland, bringing the total number here to 6,225. No further deaths were reported.
Eight people are currently being treated in hospital. Three are in intensive care.
The department added: "The seven-day rolling average for new cases has more than doubled in the last week and there is a further increase in test positivity. This is partly due to increased testing in the context of the Test, Trace and Protect service.
"However, community transmission has gone up and hospital admissions have also begun to rise, though they remain at a low level."
Data shows three confirmed outbreaks in care homes here, compared with one on Wednesday. Six other care homes have suspected outbreaks.
In the Irish Republic, 92 more cases of Covid-19 were confirmed. The Republic's total has reached 26,929. No further deaths were reported.
Separately, analysis by the Public Health Agency (PHA) shows clusters of the virus across several districts.
Since the start of contact tracing on May 24, 11 clusters with five or more people have been identified.
Four of the 11 were recorded in the Newry, Mourne and Down District Council area, with three others in the Mid and East Antrim region.
The rest were recorded in Antrim and Newtownabbey, Ards and North Down, Armagh City, Banbridge and Craigavon and Causeway Coast and Glens Borough Council.
In addition, 20 clusters across Northern Ireland with fewer than five people have been reported.
A cluster is defined as two or more laboratory-confirmed cases of Covid-19 among people associated with a key setting within a 14-day period.
Key settings which have seen clusters to date since May include workplaces, retail or hospitality premises, domestic gatherings and sporting settings.
Dr Gerry Waldron, head of health protection at the PHA, said: "This disease has the potential to make its presence felt in any community, as we have seen with clusters appearing across a number of council districts."
Dr Waldron added that speculation around current clusters was not helpful.
He said: "We will not be commenting on individual cases of Covid-19 or going into the detail of every incident that emerges, as this could lead to people being identified, creating stigma and focusing attention on individuals, families or groups, (deterring) others with symptoms coming forward to be tested."