The Vancouver, Canada-based company undertook a voluntary shutdown, sending all employees and contractors for COVID-19 protocol training.
Milling of ore is expected to resume next week.
The company said COVID-19 testing and tracing were embedded in the company's operations.
For the three months ended September 30, Topia produced on average 1,400oz gold-equivalent per month and accounted for about 9% of the company's revenues.
Great Panther expects to produce 146,000-158,000oz Au-eq in 2020 at all-in sustaining costs of US$1,150-$1,250/oz, with the Tucano openpit in Amapa, Brazil, producing the lion's share.
Shares in the company (TSX:GPR) last traded at $1.03 in Toronto, capitalising it at $365 million (US$287.3 million).