(Bloomberg) -- Shares of Covid-19 vaccine developers in Asia may get some relief after the German Chancellor rejected a U.S. proposal to waive patent protections for coronavirus shots.In the U.S., Pfizer Inc., BioNTech SE, Novavax Inc. and CureVac NV all pared an earlier slump after initial news the U.S. supported discussions for a waiver of the rights to develop vaccines. The Biden administration’s plan would create “severe complications” for the production of vaccines, a German government spokeswoman said Thursday in an email.Pfizer reversed a bulk of its decline close 1% lower and BioNTech, which tumbled as much as 15% earlier, ended down 1.6% after Germany’s announcement. Moderna Inc. pared its steepest decline since Feb. 23 to trade 1.4% lower. CureVac erased almost half of its drop and NovaVax reversed its slump to close 0.5% higher.In Thursday’s trading session, stocks linked to vaccine makers fell across Asia.Shanghai Fosun Pharmaceutical Group Co., which has the rights to develop and market BioNTech’s shot in China, plunged 14% in Hong Kong, the most ever. CanSino Biologics Inc., which makes one of China’s domestic vaccines, tanked 15%. In Japan, JCR Pharmaceuticals Co., a local partner for AstraZeneca Plc’s vaccine, slid 1.4%.Some analysts had urged for caution to the news prior to Merkel’s announcement. The Biden administration’s plans will only open up a negotiation at the WTO and other countries and members remain unwilling, said Barclays analyst Carter Gould in a note.For Evercore ISI analyst Umer Raffat, U.S. support didn’t mean it was a “100% done deal” as other countries are also opposed. It “remains to be seen if U.S. leadership’s position sways others,” Raffat wrote in a note.U.S. support for a proposal to waive intellectual-property protections for Covid-19 vaccines might be good news for the global inoculation campaign, but it’s an unwelcome turn for firms whose share prices have been buoyed by profits from coronavirus shots.With many countries struggling with a resurgence of the virus, U.S. Trade Representative Katherine Tai said Wednesday the Biden administration will take part in negotiations for the text of a waiver of the rights at the World Trade Organization. The European Union said Thursday it was willing to participate.Big BusinessVaccines have been a big business for the firms that make them, with Pfizer, BioNTech’s partner outside of China, raising its forecast for 2021 vaccine sales to $26 billion just this week. Shares of many of the U.S.-listed companies had fallen late in Wednesday’s regular trading session after Tai’s comments.Read more: Analysts say investor fears of U.S. vaccine waiver support are overblownThe U.S. move “probably isn’t great news for the vaccine manufacturers who will now face generic copies of their vaccine, but as the mutation of the virus has shown, continued research and innovation will be needed and that should provide those companies with future earnings from newer vaccines so I would expect the impact to be short-lived and possibly limited,” said Olivier d’Assier, head of APAC applied research at Qontigo GmbH.The International Federation of Pharmaceutical Manufacturers & Associations condemned the move as “disappointing.”“A waiver is the simple but the wrong answer to what is a complex problem,” the group said in a statement. “Waiving patents of Covid-19 vaccines will not increase production nor provide practical solutions needed to battle this global health crisis.”(Updates with Asian moves)For more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2021 Bloomberg L.P.