Acting state health commander Dale Webster provided an update via an interview on commercial radio on Wednesday morning - rather than through usual communications channels - to confirm the testing results.

He said the 17 close contacts would continue to be tested during the 14 days since their contact with the COVID-positive 15-year-old, who arrived at Launceston Airport on Friday and was infectious with the Delta variant for a brief period in the community by visiting Newnham IGA maskless on Saturday.

Mr Webster said it was still too soon to say if the teenager had not passed on the virus to another close contact.

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"What it means is that while they were in the community, the people on the plane that came and went home, while they were actually in the community they were negative so there isn't going to be further on spread because they were negative in the community," he said.

"But it doesn't mean they're out of the woods, so we'll continue to test them at a number of points over the 14 days after first contact."

Mr Webster said another case was likely from within the household, but that this would not pose a risk to the community.

"At some point in that 14 days you would expect we would have another case. You would hope not, but what we're seeing in other states is usually if there's one case in a household, you'll find that there's a second case in that household," he said.

"So, it's inevitable that we'll have a second case at some point."

The 35 casual contacts are in quarantine and will be tested on either Wednesday or Thursday.

The Wellington Street testing facility carried out 274 tests on Tuesday, and mobile testing buses will be used in the northern suburbs in the coming days, Health Minister Jeremy Rockliff said.

There were 880 COVID tests carried out in Launceston on Tuesday.

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There have also been 13,000 people in home quarantine in Tasmania this year, with the Newnham teenager the second recorded breach.

Mr Webster said there would be a review of the program.

"Overall, it's a successful program, but of course we will review it and make sure that we've got process in place," he said.

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"We're not going to sit on our hands and say, oh only the second case in 13,000, but I think we can say that most people do the right thing by saying that in 13,000 cases we've had one or two breaches.

"That means we need to review it, because one breach is too many."

Public Health typically sends out COVID community updates to all Tasmanian media to be shared with a wide audience, or provides updates via a press conference in Hobart, but Wednesday's update was only given on commercial radio.

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