A complete timeline of what’s going on with the AstraZeneca COVID vaccine

April 1, 2021, 6:54 PM UTC
Updated April 8, 2021, 12:47 PM UTC

AstraZeneca, the British-Swedish pharmaceutical giant based in Cambridge, England, has little track record in vaccines, but it managed to score a coup by partnering with scientists at the University of Oxford’s Jenner Institute to help bring its COVID-19 vaccine to market. The company penned deals to deliver billions of vaccines around the world.

Yet, of the major vaccine in the global market, AstraZeneca’s has had the roughest ride. Between halted trials, confusing data, and communication mishaps, the company is now facing suspended vaccinations and a decrease in trust in its vaccine.

Fortune is following this story. Here’s the latest news.

April 7, 2021—The European Union’s medical regulator, the European Medicines Agency (EMA), says the very rare blood clotting conditions that have affected a handful of people after receiving the AstraZeneca vaccine are likely caused by the jab and orders the company to carry out more tests to investigate the exact reason. But it says that given the greater risks of COVID-19 itself and the lack of alternatives so far in Europe, that the vaccine should continue to be given. Meanwhile the British regulator, the Medicines and Healthcare products Regulatory Agency (MHRA), says that while it can’t be certain yet of the link, it is recommending that healthy adults under the age of 30 be given a different vaccine in places where one is readily available. The news will likely make people more hesitant to take the vaccine, which has already suffered from doubts about its efficacy, safety and supply.

March 30, 2021—Some German cities and regions, including Munich and Berlin, suspend distribution of AstraZeneca’s vaccine to people under the age of 60 over continued concerns about unusual blood clotting incidents potentially linked to the jab. Canada also stops giving the vaccine to those under 55 based on similar fears.

March 26, 2021—The EU authorizes a manufacturing plant owned by the company Halix near the Dutch city of Leiden to begin producing AstraZeneca vaccine doses for distribution in the bloc. But the plant is controversial because the company has wanted to send doses produced there to the U.K.

March 25, 2021—AstraZeneca releases updated results from its U.S. clinical trial, including more up-to-date data, showing that its vaccine is 76% effective. Still, it may not be enough to repair the vaccine’s reputation in the U.S., with many questioning whether the country, which has already approved three coronavirus vaccines, will even need AstraZeneca’s jab.

March 23, 2021—In a stunning development, the U.S. National Institute of Allergy and Infectious Disease (NIAID) issues a middle-of-the-night statement warning that AstraZeneca may have used “outdated” data that provided an “incomplete” picture of its effectiveness. The agency makes the announcement after the Data and Safety Monitoring Board, a group of independent experts that help NIAID oversee the COVID-19 vaccine trials that have received U.S. government support, wrote a scathing letter to both NIAID and AstraZeneca saying the company may have deliberately tried to make its results seem better than they were. AstraZeneca says that the interim results were based on a “pre-specified” cutoff date for the data of February 17 and that a review of more recent data showed results that were “consistent” with the figures it used in its press release. The controversy badly dents AstraZeneca’s already battered credibility, not least with the U.S. government.

March 22, 2021—AstraZeneca announces interim results from its U.S. clinical trial, saying the vaccine was 79% effective against symptomatic COVID-19 and 100% effective against hospitalization and death. The company hopes the results of the 30,000-person study in the U.S. and South America will finally clear the way for the vaccine to be approved by the U.S. FDA.

March 18, 2021—After a review, the European Medicines Agency concludes the AstraZeneca vaccine is “safe and effective,” clearing the way for the vaccine rollout in Europe to resume.

March 16, 2021 –A number of other European countries, including Germany, France, and Italy, also suspend distribution of the AstraZeneca vaccine amid concerns about clotting even as the European Medicines Agency and the World Health Organization say the vaccine is safe. The suspensions are another blow to already faltering vaccination efforts in Europe. Meanwhile, Thailand joins the list of countries that have authorized the vaccine.

March 11, 2021—Denmark stops rollout of the AstraZeneca vaccine because of concerns about dangerous blood clotting among some who received the jab. The company’s stock falls on the news. AstraZeneca insists that the number of clotting incidents reported so far are actually fewer than would occur normally for the millions of people who have now been given the inoculation worldwide so far.

March 5, 2021—In an about-face, the German government agrees to authorize the AstraZeneca vaccine for use in those over 65.

March 4, 2021 –Italy blocks a shipment of AstraZeneca vaccine bound for Australia as the company’s fight with Europe over the lack of supplies there intensifies.

February 22, 2021—The Serum Institute of India, AstraZeneca’s manufacturing partner in that country and for many other low- and middle-income countries, says the Indian government has asked it to prioritize production for India, possibly delaying doses for other countries.

February 15, 2021—Oxford University begins a clinical trial to test how the AstraZeneca vaccine works in children.

February 8, 2021—Scientist in South Africa say that the AstraZeneca vaccine seems to be ineffective at preventing mild to moderate COVID-19 among those infected with the B.1.351 variant that first emerged in that country. The country stops rollout of the vaccine as a result. AstraZeneca says it thinks the vaccine still probably prevents severe cases of the disease.

February 5, 2021—Oxford scientists say that the vaccine is effective against the B.117 “U.K.” variant of the coronavirus.

February 3, 2021—Oxford and AstraZeneca publish more data from clinical trials showing that a single dose of the vaccine cuts coronavirus transmission by about two-thirds and that it is 76% effective at preventing symptomatic COVID-19. The trials also find that it is more effective to delay the second dose of the vaccine for 12 weeks rather than giving it sooner.

January 29, 2021—The European Medicines Authority approves the AstraZeneca vaccine for use in all adults, but adds that the initial clinical trials did not include enough people over the age of 55 to be certain of the effectiveness in that age group.

January 28, 2021—German health regulators question whether there is enough data about how well AstraZeneca’s vaccine works in those over 65 in order to approve it for use in that age group. A government advisory panel recommends against approving the vaccine for older adults. Meanwhile, French President Emmanuel Macron tells reporters that the AstraZeneca vaccine is “quasi-ineffective” in those over 65. The company insists the vaccine is effective for older adults and that data from initial use in the U.K. backs up this claim.

January 25, 2021—AstraZeneca infuriates European Union politicians when it informs them that it will be able to supply the 27-nation bloc with only about 40% of the vaccine doses it promised during the first quarter because of manufacturing problems at its European facilities. The politicians insist AstraZeneca must stick to its contract. Soriot inflames tensions by insisting the contract obligates AstraZeneca only to make a “best effort” to meet the targets mentioned in the contract. The EU consider imposing export controls to prevent any AstraZeneca doses from being sent to the U.K. or other countries until Europe receives the doses it was promised.

December 30, 2020—The U.K. becomes the first country to approve AstraZeneca’s vaccine.

November 23, 2020—AstraZeneca and the University of Oxford announce the initial results of the Phase III clinical trials in the U.K., Brazil, and South Africa. The study finds the vaccine safe and effective, but the results are presented confusingly, combining data from trials conducted with different protocols and giving out three different efficacy figures. The company says that a “blended average” showed the vaccine was about 70% effective. But in one small subgroup of the clinical trial, in which participants were given a half-dose of the vaccine and then a full-dose booster weeks later, the vaccine seemed to be 90% effective. In the larger group given two full doses, it was only 62% effective. The presentation puzzles virologists. Confusion deepens when AstraZeneca officials tell reporters the half-dose regimen is the result of a mistake. Oxford scientists initially dispute this characterization, noting that they knew they were giving people half-doses. It also emerges that the subgroup that received this half-dose regimen included no one over the age of 55, raising further doubts about how to interpret the study’s high efficacy figures. Some experts also question whether enough older adults were included in either regimen to gauge effectiveness in those over 65.

November 19, 2020—Oxford researchers publish more data in The Lancet showing that the vaccine they are developing with AstraZeneca elicits a strong immune response in older adults. The finding is important because the elderly are most at risk from COVID-19.

November 9, 2020—Pfizer beats AstraZeneca to become the first major pharmaceutical company to announce the results of its Phase III clinical trials. The company says its jab is more than 90% effective, increasing the pressure on AstraZeneca to show that its vaccine is also highly effective.

September 8, 2020—STAT News breaks the story that clinical trials of the vaccine have been halted globally after a volunteer in the U.K. clinical trial develops serious neurological symptoms. An independent review board later concludes the symptoms were unlikely to be caused by the vaccine. AstraZeneca badly mishandles communications around the incident: The news of the trial pause blindsides U.S. government officials, straining the company’s relationship with the National Institutes of Health, which has been helping to oversee the vaccine clinical trials in the U.S., and the Food and Drug Administration. CEO Pascal Soriot compounds problems by revealing on a conference call with financial analysts that the U.K. clinical trial had been paused briefly in July when another volunteer also developed neurological symptoms. Although no link to the vaccine was found in that case either, the manner in which Soriot disclosed the information angered many health experts, raising concerns about transparency. Although clinical trials in most of the world resumed on September 13 after a one-week pause, in the U.S. the clinical trial is kept on hold for seven weeks, until October 23, as AstraZeneca struggles to provide additional data requested by the FDA.

September 1, 2020—The company begins its large-scale Phase III human clinical trial of the vaccine in the U.S.

August 10, 2020—With its vaccine in pole position to be the first approved globally, Pascal Soriot, AstraZeneca’s CEO, basks in the spotlight. The vaccine drive represents a capstone on his seven-year campaign to turn around the once-struggling pharmaceutical company. Investors flock to AstraZeneca’s shares since the tie-up with Oxford is announced, sending them to all-time highs and making the company the most valuable in the FTSE 100 share index.

July 20, 2020—The AstraZeneca vaccine clears a key safety hurdle as the University of Oxford publishes the results of initial Phase I human clinical trials in the medical journal The Lancet. The results show the vaccine is safe and seems to produce strong immune responses based on lab tests of blood samples of those inoculated.

June 4, 2020—The company signs two landmark agreements with two international vaccine organizations, CEPI and Gavi, to provide 1.3 billion doses to low- and middle-income countries. The organizations agree to pay AstraZeneca $750 million to cover the cost of producing the first 300 million doses so they are ready by the end of the year. Separately, the company announces a partnership with the Serum Institute of India to provide 1 billion doses for India and other low- and middle-income countries, with the first 400 million doses to be available by year-end. The vaccine is seen as important for immunizing much of the world because doses are relatively inexpensive—costing less than $5 per shot in most cases—and can be stored at normal refrigerator temperatures, an important consideration given the logistical issues surrounding Pfizer’s vaccine, which needs storing at super-low temperatures.

May 21, 2020The U.S. government inks an agreement with AstraZeneca for 300 million doses of its vaccine. It agrees to pay the company $1.2 billion to help cover the cost of clinical trials and for setting up manufacturing facilities able to churn out billions of doses.

May 18, 2020—AstraZeneca signs a deal with the U.K. government to supply up to 30 million doses of the vaccine by as soon as September and to provide 100 million doses by the end of the year.

April 30, 2020—AstraZeneca’s vaccine uses a modified chimpanzee virus to deliver instructions to the body to make the coronavirus spike protein. This in turn triggers an immune response. The scientists, who have already begun human clinical trials of their vaccine in the U.K., have been in negotiations with U.S. pharma giant Merck but come under increasing pressure from the U.K. government to find a British-based partner. As part of the deal, the company pledges to play a leading role in helping to vaccinate the world by producing billions of doses. It also pledges to make no profit on the vaccine effort until the pandemic is over.

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