CSL's update on Monday seeks to demonstrate in the clearest terms the benefit of the acquisition announced in December. Some analysts had questioned the tie-up between CSL, which specialises in blood plasma-based treatments for rare diseases, and Vifor, which makes iron-based treatments for iron deficiency.

The former Australian government laboratory, now the country's fourth-largest company by market capitalisation, previously flagged a rebound in annual profit in the year to June 2023 to the range of $2.4 billion to $2.5 billion. With Vifor's contribution, profit would now be in the $2.7 billion to $2.8 billion range, it said on Monday.

"Vifor Pharma is the perfect fit for CSL," CSL CEO Paul Perreault told an investor briefing.

The Swiss company was "only in about 20 countries, and they haven't launched every product in 20 countries", he added. "There's plenty of room for growth and expansion to service patients around the globe."

In particular, Vifor expected to grow sales 10% per year in the medium term as hospitals in the United States admitted more people for treatment of iron deficiency due to lifting of COVID-19 restrictions, said Hervé Gisserot, general manager of the newly acquired unit, now called CSL Vifor.

CSL Vifor makes 38% of its sales from a drug for people with iron deficiency and anaemia.

Asked about concerns CSL Vifor's future sales may be vulnerable to competition from generic rivals once patents expire, Perreault said, "I thought plasma manufacturing was hard; iron is harder."

CSL shares were down 1.6% midsession, in line with the broader market.

"Whilst we believe there have been short-term sales declines for CSL Vifor in the U.S., likely due to COVID, we believe CSL Vifor is a relatively high-growth, high barrier-to-entry business," said Jefferies analysts in a client note.

(Reporting by Byron Kaye; Editing by Muralikumar Anantharaman)

By Byron Kaye