Anyone who has booked a jab at the Cliffs should arrive no more than five minutes before their appointment.
The centre will also be vaccinating health and care staff who are being urged to get their first dose as soon as possible to protect themselves and others.
NHS staff are also visiting those who are housebound and unable to travel to any of the vaccine sites in Southend.
Why is the vaccine centre at the Cliffs?
The theatre has of course been closed for sometime now because of the coronavirus pandemic and latest lockdown.
Bosses say it was the ideal location for a mass vaccine site.