Every pupil has been given a PCR test at a Wigan high school after a Covid outbreak.
The decision to test the 612 pupils came after 68 positive cases at Shevington High School in the space of 10 days.
Students have also been told to wear masks again, both in communal areas and in the classrooms, after public health bosses found there was evidence of class transmission.
Read more: Siblings of pupils testing positive told to isolate amid rising cases
The borough's director of public health Professor Kate Ardern said they moved quickly to 'introduce a suite of measures' including the targeted onsite testing of pupils, which took place on Monday.
Youngsters in the three worst affected forms were also given lateral flow tests, so that anyone showing as positive could isolate immediately, rather than waiting for the PCR results, which they're expecting back today (Thursday) or tomorrow.
"We've taken a very comprehensive approach to the testing," said Prof Ardern. "The school has gone above and beyond to manage the situation and they've been doing all the right measures we would expect a school to undertake - such as not having open days with mass gatherings of people, having one-way flow systems and a focus on hand hygiene.
"We decided to bring back face coverings, not just in communal areas but in class as well as we were seeing some evidence of intraclass transmission, so that seemed to be sensible."
Next week the school is expecting to start vaccinating pupils in line with the vaccination programme for 12 to 15-year-olds across England.
However, because anyone testing positive for Covid can't be vaccinated until 28 days after a positive PCR, Shevington's outbreak will delay a number of pupils getting the jab.
"One of the challenges of having high transmission rates in somewhere like a school means it does delay the ability to take up the offer of the vaccine," said Prof Ardern.
As many pupils as possible will get the vaccine next week, with a 'mop-up' session planned for a later date to immunise the ones who miss out.
Another measure being considered by Wigan council is to ask the siblings of positive cases to isolate too - a step already taken in Trafford.
"If you've got siblings in a household with a positive case, they're more likely to be at risk of developing it themselves," said the professor. "So it's looking likely we'll do that as an another measure."
