The Waikato District Health Board says it can't offer wider Covid-19 testing for people who attended the St Patrick's Day party linked to one of the country's largest clusters.
All staff and students at Auckland's Marist College have been offered testing this week regardless of whether or not they are symptomatic. One student has since tested positive, bringing the total number of cases linked to the school to 95.
Director-General of Health Dr Ashley Bloomfield said it was unlikely the student was infectious and the test described as a "weak positive" was probably due to the illness being in its late stages.
Waikato DHB Medical Officer of Health Richard Hoskins said it was considering testing asymptomatic contacts of recent cases linked to the Matamata cluster who have never been tested, but the DHB was not able to offer voluntary testing.
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"We don't have a list of everybody who attended that event... Marist College has a register of all of its students and their families and teachers."
There "may well" be someone who would return a weak positive test, like the Marist College student, but if they were infectious, it would be in a very minor way, he said.
Seventy-six positive cases have been linked to the Redoubt Bar in Matamata which hosted the St Patrick's Day party on 17 March.
Health officials believe infectious people were at the bar several days before and after the event, Dr Hoskins said.
"A lot of people will say 'I got it at the St Patrick's Day event' but we've got a few who were there the night before or the night after, or a couple of days either side and also part of that cluster."
The cluster's index case, who was not a staff member at the bar, travelled back from Ireland via Dubai on 15 March and worked for several days at the bar while they were infectious, he said.
"A person that had recently returned from overseas, and was not an employee of the venue at the time, did spend time at the venue while infectious with Covid-19.
Dr Hoskins earlier said the infected person worked at the bar, and has apologised for misinterpreting the information.
Four staff members later tested positive, Dr Hoskins said.
One week after the St Patrick's Day party, on 25 March, Dr Hoskins said an increasing number of tests started to return positive results.
"As soon as we made the common event... made the link back to the venue and then to the event, and we knew it had been a big event, we were going 'this is probably going to be quite big'."
Dr Hoskins expects to be able to declare the cluster closed in about a week.
A cluster can be declared closed after there are no new classes linked to it in 28 days.
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