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AstraZeneca vaccine shows 79% efficacy in phase III trial

The company will now be pursuing Emergency Use Authorization from the FDA with an eye toward distribution.

Jeff Lagasse, Associate Editor

(Photo by Halfpoint Images/Getty Images)(Photo by Halfpoint Images/Getty Images)

AstraZeneca's COVID-19 vaccine has just undergone a phase III trial in the U.S., demonstrating 79% efficacy at preventing symptomatic COVID-19 and 11% efficacy at preventing severe disease and hospitalization.

Vaccine efficacy was consistent across ethnicity and age the drugmaker said on Monday. Notably, among people 65 and older, vaccine efficacy was 80%. The vaccine was well tolerated, and the independent data safety monitoring board (DSMB) identified no safety concerns related to the vaccine. 

The DSMB conducted a specific review of thrombotic events, as well as cerebral venous sinus thrombosis (CVST), with the assistance of an independent neurologist. The DSMB found no increased risk of thrombosis or events characterised by thrombosis among the 21,583 participants receiving at least one dose of the vaccine. The specific search for CVST found no events.

AstraZeneca's offering was met with controversy after several countries temporarily suspended its use following reports of blood clots in some people. Health experts criticized the move due to a lack of data. Independent reviews have found no increased risk of blood clots due to the vaccine.


The trial results come as vaccine administration is ramping up across the country. Currently, states are vaccinating their residents with offerings from Pfizer, Moderna and Johnson & Johnson. A fourth FDA-approved vaccine would likely bolster supply at a time when eligibility is expanding to wider swaths of the population.

This AstraZeneca-led phase III trial included two doses administered at a four week interval. Previous trials had shown that an extended interval of up to 12 weeks demonstrated greater efficacy, which was also supported by immunogenicity data. This evidence suggests administration of the second dose with an interval longer than four weeks could further increase efficacy, and accelerate the number of people who can receive their first dose.

The vaccine can be stored, transported and handled at normal refrigerated conditions (2-8 degrees Celsius or 36-46 degrees Fahrenheit) for at least six months and administered without the need for preparation within existing healthcare settings.

Among participants in the interim analysis, about 79% were white/Caucasian, 8% Black/African American, 4% Native American and 4% Asian, while 22% of participants were Hispanic.

About 20% of participants were 65 and older, and roughly 60% had comorbidities associated with an increased risk for progression of severe COVID-19, such as diabetes, severe obesity or cardiac disease.

The next step for AstraZeneca is to analyze the data and prepare for the primary analysis that will be submitted to the FDA for Emergency Use Authorization in the coming weeks. In parallel, the primary analysis will be submitted for publication in a peer-reviewed journal.


President Joe Biden pledged this month to make all adult Americans eligible for a coronavirus vaccine by May 1, but many states have accelerated their timelines. Biden also announced plans for a national website to help facilitate vaccination scheduling and administration. The website will be launched by May 1.

In a fact sheet, the White House also promised to create an 800 number that would serve the same purpose for those without access to the internet and to deploy technology teams to help support states' websites.

On the reimbursement front, Medicare is now paying higher reimbursement rates for hospitals, physicians, pharmacies and others to administer the vaccine. The Centers for Medicare and Medicaid Services has increased the Medicare payment amount to $40 to administer each dose, an increase from about $28 to $40 to administer a single dose, and an increase from about $45 to $80 for the administration of vaccines requiring two doses.

The exact payment rate for administration of each dose of a COVID-19 vaccine will depend on the type of entity that furnishes the service and will be geographically adjusted based on where the service is furnished, CMS said.

Meanwhile, the vaccine is increasingly available at more locations. CVS Health, for example, has expanded the number of locations that are offering vaccines, nearly doubling the number of states in which eligible patients can receive their shots through the health giant.

Through the Federal Retail Pharmacy Program (FRPP), the company is now administering vaccines in roughly 1,200 stores across 29 states and Puerto Rico.

Twitter: @JELagasse
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