AstraZeneca’s vaccine is key to ending the global economic slump caused by the coronavirus. But a series of missteps by the drugmaker and new concerns over blood clots risk undermining public confidence in the shot and delaying the recovery. European drug regulators said there was a possible link between the Oxford-AstraZeneca Covid-19 shot and rare blood clots on Wednesday, but stopped short of recommending its use be limited. UK authorities recommended that people under 30 take alternative vaccines. It’s the latest setback for AstraZeneca\n \n (AZN), which has faced criticism over its communication with the public and regulators, the design of its vaccine trials and severe production delays that have slowed the rollout of shots in Europe. Authorities maintain that the benefits of the vaccine far outweigh the risks for most age groups. Yet shifting guidance and blood clot worries risk snarling distribution efforts in many countries. Germany suspended the use of the AstraZeneca vaccine last week in people under 60 years old, while Australia said Thursday it will not give it to people under the age of 50. The safety questions could have even bigger implications for developing and middle-income countries, many of which are relying on the shot to unlock their economic comebacks because it’s cheaper than other vaccines and can be stored more easily. Many are accessing it through Covax, a global vaccine-sharing program, which has secured more than half its supply from AstraZeneca as of March. Overall, orders for an estimated 2.4 billion doses of AstraZeneca’s vaccine have been confirmed, according to the Duke Global Health Innovation Center. That’s roughly 28% of the global total. “There’s a lot of uncertainty here,” said Ben May, director of macro research at Oxford Economics. He said the AstraZeneca developments weren’t enough to revise near-term growth forecasts, but that he would keep monitoring the situation closely. The World Health Organization said in a statement Wednesday that “based on current information, a causal relationship between the vaccine and the occurrence of blood clots with low platelets is considered plausible but is not confirmed.” AstraZeneca said that nearly 200 million people around the world have already received its vaccine, and that reviews by EU and UK regulators “reaffirmed the vaccine offers a high-level of protection against all severities of Covid-19 and that these benefits continue to far outweigh the risks.” A rough start AstraZeneca received emergency use authorization from the United Kingdom in late December and the European Union one month later. Because the vaccine was less expensive and could be stored at higher temperatures than ones developed by Pfizer\n \n (PFE) and Moderna\n \n (MRNA), it was heralded as a breakthrough, particularly for less affluent countries that lack sophisticated logistics networks. The company also generated lots of goodwill by pledging to supply its vaccine at no profit during the pandemic, and by partnering with the Serum Institute of India, which agreed to produce more than 1 billion doses for low and middle-income countries. AstraZeneca has already provided over 30 million doses to more than 58 countries through Covax. However, a series of missteps generated a string of bad headlines for the Anglo-Swedish drugmaker. The first issue cropped up in November, when the company faced questions about data from large-scale trials. Volunteers received different doses due to a manufacturing error, creating confusion about its actual effectiveness. AstraZeneca did not mention that a mistake caused the dosing discrepancy in its initial announcement, generating concerns about a lack of transparency. “I hate to criticize fellow academics, or anyone for that matter, but releasing information like this is like asking us to try and read the tea leaves,” Dr. Saad Omer, a vaccine specialist at the Yale School of Medicine, said at the time. More stumbles followed. Germany’s vaccine commission said in January that AstraZeneca’s shots shouldn’t be given to people older than 65, citing insufficient data for the age group. France also initially limited AstraZeneca vaccines to those under 65. Both countries changed course last month. Jeffrey Lazarus, head of the health systems research group at the Barcelona Institute for Global Health, previously told CNN Business this was an “easily avoidable” issue tied to trial design. Had the vaccine rollout been smooth, such stumbles may have been forgotten. But continued shortfalls in supply of the AstraZeneca shots in Europe, which is now mired in a third wave of coronavirus infections, have triggered huge political blowback in the bloc. Leaders have imposed restrictions on vaccine exports. “If we had received the 100% of AstraZeneca’s vaccines that were contracted to us, the European Union would be at the same level today as Great Britain in terms of vaccines,” European Commissioner Thierry Breton said in a recent interview with Le Parisien newspaper. “So I can say that the pocket of turbulence we have experienced is solely due to AstraZeneca’s failure to deliver.” AstraZeneca’s future role The company also ran afoul of US regulators last month when it submitted trial data from the country. The US National Institute of Allergy and Infectious Diseases expressed concerns that the efficacy information submitted was “outdated.” AstraZeneca quickly sent in revised data, but Dr. Anthony Fauci, the agency’s director, called it “an unforced error.” Now, as fears about rare blood clots force governments around the world to reassess the risk-benefit analysis of providing shots to all age groups, the United States has indicated it does not need AstraZeneca’s doses. “We have enough very good vaccines,” Fauci, who also serves as chief medical adviser to President Joe Biden, told CNN on Wednesday. Not all countries will have that luxury, however. India, for example, is leaning heavily on AstraZeneca’s shot as it tries to fight back against an alarming spike in cases. Lazarus said Thursday that if wealthier nations decide they want to reduce their reliance on AstraZeneca, he hopes shots can be sent to other nations in need, since the data still indicates it’s safe and effective. “There are plenty of other countries that don’t have other options because of the logistics … and because of the cost,” he said. He does worry, however, that all the bad publicity could affect people’s willingness to accept an AstraZeneca vaccine when it becomes available. “This is definitely going to impact the reputation of the AstraZeneca vaccine,” Lazarus said. “[It] will lead to lower uptake.” That could be bad news for the global economic recovery. This week, the International Monetary Fund upgraded its forecast for global growth this year to 6%. But that estimate depends in part on the pace of the vaccine rollout. “Anything that might effectively reduce vaccine availability is obviously not good news,” said May of Oxford Economics. The vaccine “is still usable for the most vulnerable sections of the population,” he noted. But coupled with supply shortages, new restrictions could complicate the recovery in countries where AstraZeneca’s vaccine is central to pandemic exit strategies, May said.