Shire Health won the business after a four-way competitive pitch that included incumbent agency Chandler Chicco Agency.
CCA had handled the account for a year until last December, working on the UK launch of Pegasys in July.
It is estimated between 200,000 and 400,000 people in the UK have hepatitis C, a liver disease that occurs when blood or body fluids from an infected person enters the body - often through sharing needles during intravenous drug use.
Shire Health associate director Deanne Wallace and account director Sian Boisseau lead a four-strong account team, reporting to Roche PR manager Rebecca Hunt and director of corporate affairs Sarah Ridout.
Boisseau defined the target audience - predominantly drug-users and former drug-users - for the Pegasys promotional campaign as 'hard to reach', saying the campaign would focus on groups such as drug action teams and voluntary groups.
When Pegasys launched, CCA ran a one-week campaign called Responsible Rebels, which encouraged those who had formerly used drugs to take a hepatitis C test.
Meanwhile, Roche is looking to boost the size of its in-house comms department.
Geoffrey Henning has moved internally to fill the role of community relations manager, a newly created post. Shazia Sheikh has moved from PR copywriter to PA executive and Roche is to recruit two further PR executives, taking the in-house comms team to ten.