The developer of the NHS Covid-19 app has been awarded a £10million six-month extension to continue delivering contact-tracing services.

Swiss firm Zühlke Engineering will continue to build and operate the NHS Test and Trace app and supporting systems, including the app’s cloud services, public dashboard, and QR-code posters.

The firm is the main commercial partner of the contact-tracing app and has worked on the service since development began in early 2020.

The newly published procurement contract, valued at £10.26million, began on March 15 2021 and is valid until September 30 2021. It takes the cumulative total of contracts award to Zühlke for development and support of the contact-tracing app to more than £22m.

A breakdown of the discounts included in the £10m costs, as well as information on out-of-hours charges and expenses limits, was redacted.

Zühlke will be required to provide “ongoing analysis, design and development of new features” as well as “response, recovery and resolution of production incidents” relating to the app, its public dashboard, self-isolation payment gateway and QR-code poster creation.

In addition, the company will be expected to provide senior technical oversight and engineering services on a case-by-case basis, including on-call and out-of-hours support.

“There may need be a need for flexibility in terms of the number of staff deployed to best meet the buyers [Department of Health and Social Care] requirements,” the contract states.

The app will be regularly reviewed and updated to ensure it is aligned with the overall goals of NHS Test and Trace, the contract added.

On top of developing new features, Zühlke will be expected to support the scalability of the app which the contract states has been designed to support at least 50 million downloads.

Each release of new software will be made available as Open Source.

The total cost of the contact-tracing app was expected to top more than £35 by the end of the 2020/21 financial year. Some £25 million was expected to be spent in 2020/21, while a further £10 million was spent developing the original operating model that was eventually abandoned following heavy criticism relating to accuracy, data protection and privacy.

Wolfgang Emmerich, founder of Zühlke Engineering, previously told Digital Health News the app would be an “important pillar” in controlling the spread of Covid-19 as England comes out of lockdown.

He said the app has been updated weekly since its launch “as policy and science changes” and will continue to be updated as lockdown restrictions are eased.

Since the app’s launch in September 2020 it has been downloaded 21.63 million times, with 1.7 million users advised to self-isolate following close contact with someone who had tested positive, Department of Health and Social Care figures from February 2021 show.

Government ministers are currently reviewing data to determine whether all Covid restrictions can be lifted by June 21, which would include a return to clubs and bigger events.

For a more in-depth look at the NHS Covid-19 app, and what went wrong along the way, take a look at our timeline of events here.