AstraZeneca's COVID-19 vaccine has made headlines in the past few months due to scrutinized trial analyses, manufacturing concerns and reports of adverse events.
The vaccine has been authorized for emergency use in dozens of countries but has not yet been cleared by the FDA. AstraZeneca is expected to apply for FDA emergency use authorization in the coming weeks.
Below is a timeline of some of AstraZeneca's recent efforts to ensure its COVID-19 vaccine is safe, effective and ready for delivery.
Nov. 23, 2020: AstraZeneca published interim trial analysis saying its COVID-19 vaccine was, on average, 70 percent effective.
The interim analysis came from trials the drugmaker was conducting in the U.K. and Brazil, which tested the vaccine in two different dosing regimens. The analysis found the vaccine to be 90 percent effective when given to patients first as a half-dose, followed by a full dose at least a month later. The vaccine was 62 percent effective when administered in two full doses one month apart.
Nov. 25, 2020: The New York Times reported that some scientists were scrutinizing AstraZeneca's Nov. 23 announcement saying the drugmaker's vaccine trial data disclosures were marked by omissions and irregularities.
Responding to the criticism, the drugmaker said a manufacturing error resulted in some clinical trial participants receiving only half the intended dose of the vaccine. AstraZeneca called the error a "useful mistake" and "serendipity," according to CNBC.
Jan. 29: The European Union published a redacted version of the contract it signed with AstraZeneca Aug. 27.
This occurred shortly after AstraZeneca said it would deliver only a fraction of the doses it had agreed upon for the first quarter, citing manufacturing issues at its European production sites.
AstraZeneca denied that it had failed to deliver on its commitments and said the agreed-upon figures were targets, but not guaranteed, according to The Guardian.
"The Commission welcomes the company's commitment towards more transparency in its participation in the rollout of the EU Vaccines Strategy," the EU said.
March 12: World Health Organization Director-General Tedros Adhanom Ghebreyesus, PhD, said the European Medicines Agency reported there's no indication of a link between AstraZeneca's vaccine and blood clots. His announcement came after Iceland, Denmark, Norway and other countries had halted use of the vaccine after reports of people developing blood clots after being vaccinated.
AstraZeneca said the number of blood clots reported by people who had received its vaccine were lower than could be expected to naturally occur, according to CNBC.
The WHO and European Medicines Agency later conducted safety reviews for the vaccine and determined it was safe.
March 22: AstraZeneca said its COVID-19 vaccine demonstrated 79 percent efficacy at preventing symptomatic COVID-19 and 100 percent efficacy at preventing severe disease and hospitalization in its U.S. phase 3 trial.
March 23: Less than a day after AstraZeneca said its COVID-19 vaccine was 79 percent effective at preventing symptomatic COVID-19, the National Institute for Allergy and Infectious Diseases issued a statement saying the drugmaker's announcement may have been based on outdated data.
NIAID's statement, issued just after midnight on March 23, said that its data and safety monitoring board expressed concern that AstraZeneca's announcement was based on "outdated information from that trial, which may have provided an incomplete view of the efficacy data." The data and safety monitoring board notified AstraZeneca and the Biomedical Advanced Research and Development Authority of its concerns.
March 25: AstraZeneca issued a statement that lowered its vaccine's efficacy against symptomatic COVID-19 from 79 percent to 76 percent and maintained that it is 100 percent effective in preventing severe disease and hospitalization.
The drugmaker said its new announcement was based on 190 symptomatic COVID-19 cases that occurred among 32,449 participants in its phase 3 U.S. trial, 49 more cases than disclosed in the March 22 analysis. The new announcement also said the vaccine was 85 percent effective in trial participants ages 65 and older, an increase from the 80 percent efficacy the drugmaker reported for this group March 22.
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