The 37-year-old male Singaporean did so before his symptoms surfaced on Jan 31.
He saw a general practitioner on Feb 2, and was admitted to Khoo Teck Puat Hospital last Thursday, said the Ministry of Health.
Before that, he was on duty during Chingay 2020. The parade was held on Jan 31 and Feb 1.
He had also gone to work at Certis Cisco Centre in Paya Lebar.
He did not serve any quarantine orders after the onset of symptoms.
The man, who lives at Sembawang Drive, was confirmed to have the virus on Sunday afternoon.
A Certis spokesman said yesterday that the company is focused on providing "all necessary assistance to the affected employee and his family", and is assisting the authorities with their investigations.
"The safety of our employees is our top priority," she said.
She did not answer questions on how many Certis officers are helping to serve quarantine orders, but said that the company has taken precautions to keep its employees safe.
Measures implemented include temperature screening at all premises, regular disinfecting of surfaces, and dividing its work-force into cohorts to minimise physical contact.
She said the company also provides employees with access to safety advisories, answers to frequently asked questions and para-counselling. Travel declarations also have to be made.
The total number of infected people here is now at 45.
The other new case announced yesterday was a two-year-old Singaporean girl who was evacuated from Wuhan on Jan 30 on a Scoot flight.
She did not have symptoms when she boarded the flight back to Singapore and was quarantined upon landing. She was subsequently confirmed to have the virus yesterday.