Labour leader Andrew Little said Dr Clark had been associate health spokesman and worked closely with former deputy leader Annette King, who is relinquishing the health role.
Labour's caucus unanimously endorsed Jacinda Ardern as its new deputy leader yesterday.
''A Labour Government will reverse National's health cuts and David's skills and experience will be invaluable in communicating to the electorate how Labour will fix the health system,'' Mr Little said in a statement.
''The team I lead into this year's election is strong and determined.
''We will be working hard to show New Zealanders that there is a better way that provides fairness and opportunity for all.''
Dr Clark relinquished the economic development and trade and export growth portfolios to Stuart Nash and David Parker, respectively.
Dr Clark held on to his role as associate finance spokesman.
The reshuffle was prompted by the Mt Albert and Mt Roskill by-election wins.
New MP Raymond Huo, returning to Parliament as a list MP because Jacinda Ardern won an electorate seat, would take up the land information role.
Mrs King has picked up the state services portfolio.
The reshuffle resulted in no change for Dunedin South MP Clare Curran.
