Melbourne, April 24, 2026, 06:21 AEST
- CSL shares fell near decade lows after the U.S. military scrapped its mandatory flu vaccine rule.
- The move lands as CSL’s Seqirus vaccine arm already faces weaker U.S. flu immunisation rates.
- CSL separately disclosed a fresh A$19.4 million of share buybacks as it tries to steady investor confidence.
CSL Limited shares dropped to their lowest level since 2017 after the U.S. military ended its long-running requirement for service members to receive annual flu shots, adding a fresh demand risk for the Australian biotech group’s vaccine business.
This matters now because CSL is already under pressure. Its Seqirus unit sells influenza vaccines, the United States is the company’s largest revenue source, and investors have been marking down the stock after weaker flu vaccination trends, slower plasma recovery and a run of earnings disappointments. Reuters reported CSL’s stock fell as much as 0.8% on Thursday and was down more than 25% in 2026.
Pentagon chief Pete Hegseth said annual influenza vaccines were no longer mandatory and that troops could still take the shot voluntarily. The policy change is simple, but the market read was not: a guaranteed buyer base has become less certain at a time when flu-shot demand is already softer.
Marc Jocum, senior product and investment strategist at Global X ETFs, called the Pentagon move “incremental pressure at the worst possible time.” Hebe Chen, market analyst at Vantage Markets, pointed to “slowing earnings momentum” and said CSL had yet to “find a floor.” Reuters
CSL had warned in February that the U.S. 2025/26 seasonal influenza vaccine market was projected to fall about 6% to 8%, mostly because of lower immunisation rates and pricing in the egg-based vaccine category. Seqirus reported first-half revenue of US$1.65 billion, down 2%, while seasonal influenza revenue rose 1% despite the difficult U.S. market.
The company is not standing still. A Thursday ASX filing showed CSL bought back 148,686 shares on April 22 for A$19.44 million, taking shares bought back before that day to 5.75 million. An on-market buyback means a company buys its own shares through the stock exchange, usually to return capital and support per-share earnings.
The buyback has a ceiling of US$750 million and runs to June 30, 2026, the filing showed. CSL paid between A$128.68 and A$136.33 for the latest batch, below the A$144.44 maximum price allowed under ASX rules for that day.
The capital return sits beside a tougher operating story. CSL’s February half-year update showed revenue fell 4% to US$8.3 billion, while reported net profit after tax dropped 81% to US$401 million after restructuring costs and impairments. NPATA, a profit measure that strips out acquisition amortisation and large one-off items, fell 7% to US$1.9 billion.
Chief Financial Officer Ken Lim said at the time CSL was “not satisfied with our performance,” and the company maintained fiscal 2026 guidance for 2% to 3% revenue growth and 4% to 7% NPATA growth, excluding one-off restructuring costs and impairments. That guidance now faces a fresh test from U.S. vaccine policy.
The shift is not only a CSL issue. Sanofi, GSK and AstraZeneca also sell flu vaccines, and Reuters reported those companies and CSL Seqirus were not immediately available for comment after the U.S. military move. But CSL’s exposure stands out because Seqirus is a named strategic business and flu vaccines are a visible part of its profit mix.
The risk for the bear case is that a mandate ending does not mean every dose disappears. Some U.S. service members may still choose vaccination, and CSL has been pushing differentiated flu products and expansion in Europe. The downside is clearer: if U.S. institutional demand weakens and household vaccination rates keep sliding, CSL has less room for error in the second half.
