The number of coronavirus cases linked to the 2 Sisters factory in Coupar Angus has risen to 57.
The factory remains open and NHS Tayside's director of public health said they were in a "very different position to when there were COVID-19 cases at the factory last August".
Five months ago the poultry processing plant was at the centre of an outbreak where over 200 people tested positive.
NHS Tayside's director of public health Dr Emma Fletcher said the latest rise in cases was "an expected increase" with many of the cases being among those who are already self-isolating.
Over 80 employees are currently self-isolating as a precaution.
Dr Fletcher is chair of the Incident Management Team.
The public health chief said: "Fifty-seven cases of COVID-19 connected to the 2 Sisters food processing plant have now been identified.
"This was an expected increase, with many of the additional positive cases already self-isolating.
"The Incident Management Team remains reassured that the factory can remain open at this time as we are in a very different position to when there were COVID-19 cases at the factory last August."
Expanding on why the situation was different, Dr Fletcher pointed to additional measures having been established in the factory and the current COVID rate being much higher in the wider community.
She explained: "Firstly, 2 Sisters has put in place a number of measures to reduce the risk of transmission within the factory. These have been reviewed regularly and assurance provided by the relevant regulatory authorities.
"Secondly, the incidence of the infection in the community is much higher compared to August. Therefore, we will identify cases of COVID-19 in employees of 2 Sisters, as in any workplace, at this time.
"Many of the cases are likely to have contracted the infection outwith the factory setting.
"Thirdly, we have built on our experience from the cases at the factory last year and work closely with the factory ensuring full contact tracing is completed for all staff contacts and advice and support provided to employees affected through partner agencies of the IMT."
Contact tracing is ongoing.
Dr Fletcher said: "We can confirm that contact tracing of the positive cases to date is ongoing and over 80 employees who were working in the areas of the factory which have been identified as having been directly affected, are self-isolating as a precaution.
"The factory is continuing to work closely with NHS Tayside's public health team and Food Standards Scotland to help manage the situation."
The Incident Management Team is keeping the situation "under close review" and will meet again on Friday, January 15.
