Now, all staff, pupils and their families are being urged to get a PCR test as a precaution even if they don't have symptoms.
This follows the detection of the new ‘Delta’ Covid-19 variant - previously known as the Indian variant - in a number of staff and pupils.
The school will move to remote learning from Friday, June 4 until Friday, June 11 in a bid to reduce the spread of the new variant and will reopen on Monday, June 14.
As there are two in-service days next week this means there will be a total of four days of remote learning.
Almost all senior pupils have completed their SQA assessments, however there are still a small number who are self-isolating, and the school is making plans to support them.
Councillor Cecil Meiklejohn, Leader of Falkirk Council said: “We’re putting in the mobile testing unit to ensure that both staff and pupils can get results quickly.
"The decision that has also been made to move Falkirk High to remote learning was not taken lightly, however, we recognise the concerns of pupils, parents and staff.
“Testing remains an important part of preventing the Covid-19 virus from spreading.
"We would encourage everyone connected with the school to get a PCR test as soon as possible.”
Dr Henry Prempeh, Public Health Consultant, NHS Forth Valley, said: "Taking action now will help prevent further spread of Covid-19 which is why we are asking all pupils and staff, along with members of their households to get tested over the next few days.
“This is really important to help us identify any additional positive cases as many people with Covid-19 do not have any symptoms.”
A mobile test centre will be located at the school until Tuesday, June 8 and is open between 10am and 5pm each day.
No appointment is necessary, although all pupils under 16 must be accompanied by an adult.
Household members of pupils and staff from the school are being encouraged to get tested at a separate unit located at Abbotsford House, David’s Loan, Bainsford where capacity has been increased for PCR Covid-19 tests.
Tests at this location should be booked via www.nhsinform.scot/testinghttp://www.nhsinform.scot/testing or by calling 0300 303 2713.
Further information on Covid-19 is available on the NHS Inform website
Support for those self-isolating is available from Falkirk Council's Support for People service.