An NHS 111 call centre in Stoke Gifford temporarily closed after 20 workers tested positive for coronavirus.
The Care UK-run centre in Nicholson House in Lime Kiln Close, which provides a 24/7 service for medical advice, shut at 2pm yesterday (April 27).
It reopened at 12pm today, following a deep clean.
Over the past five days, there have been 20 confirmed cases of Covid-19 among the 260 employees at the site, the company said.
Care UK's integrated urgent care director Kevin Brown said: "The wellbeing of our colleagues and their families is always our priority and our thoughts are focused on the recovery of those testing positive.
"NHS 111 call centres fulfil a vital role in the response to Covid-19 and as many modifications as possible had already been made in Bristol and our other call centres.
"We have used meeting rooms and currently empty office space provided by other businesses to ensure all colleagues have been able to sit at alternating desks and are at least two metres apart.
"Working with the NHS nationally, we have moved many roles to a home-working basis."
Mr Brown revealed Care UK has also increased the availability of sanitiser for staff and is wiping down the workplace more frequently.
During the closure, calls were handled by other NHS 111 national providers.
"We are supporting all those affected and are continuing to review all our processes to make workplaces as safe as possible for those colleagues working in our essential NHS services," Mr Brown added.
NHS 111 is responding to enquiries from people concerned they might have coronavirus or seeking other medical advice, both in web-based assessments and phone calls.
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