Mid Ulster District Council has written to those who attended April's meeting after someone present tested positive for coronavirus.
In an email sent on Monday to those who attended the meeting in Dungannon council offices on April 23, the council advised that a person there had since tested positive.
"You were in attendance at the meeting and therefore, should you, or any member of your household, have any coronavirus-like symptoms you should self-isolate and follow the latest advise and guidance," the email continued.
"You will appreciate that under the General Data Protection Regulations it is not possible to name the individual concerned."
Speaking after the news emerged, Mid Ulster District Council said the gathering took place before regulations allowing for remote meetings were introduced.
"The council has been made aware that a person in attendance at its council meeting on April 23 has tested positive for coronavirus from a test taken on May 15, 2020," it said.
"As a result we are contacting all those who were at the meeting and advising them to self-isolate should they or members of their household show symptoms.
"While the meeting took place prior to the legislation being introduced to allow councils to hold meetings remotely, only a third of elected members attended and other councillors accessed the meeting online.
"All measures to safeguard attendees, including social distancing, enhanced cleaning and hand-washing facilities, were in place."
The council's planning committee is to meet again on June 2 with video conferencing technology in place to allow applicants and objectors the opportunity to address the meeting remotely.
The council has received over 130 planning applications since lockdown began.