It replaces the fixed site which has been providing PCR tests in Wainwright Road for the past two years but which will end its operation at 5pm tomorrow (Friday, March 4).
The new temporary site will operate from the nearby Wainwright Road car park.
It is expected to begin operating on Monday (March 7) and will continue until the end of March.
PCR tests can be booked by anyone who has Covid symptoms and needs confirmation of infection for their employer or to limit risks for vulnerable people, including those they care for.
Other PCR testing sites are available in the county at Plumpton (drive-through) and at Eastbourne, Hastings and Hailsham (walk-through).
A test can be booked at your nearest available site through the national service at www.gov.uk/get-coronavirus-test or by calling 119.
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People without symptoms who regularly come into contact with high risk individuals will not require a PCR test and can continue to test themselves at home using Lateral Flow Tests which can be ordered online at www.gov.uk/order-coronavirus-rapid-lateral-flow-tests.