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AstraZeneca vaccine found to be 3% less effective after further trial analysis

Published on 25/03/21 at 11:30am
AstraZeneca sign

AstraZeneca have revised their findings from the US study AZD1222 of their COVID-19 vaccine, announcing a 76% efficacy against symptoms of the virus, as opposed to the 79% efficacy reported on Monday.

While these primary results slightly differ from the pre-specified interim analysis, the company were also able to confirm 100% effectiveness against severe or critical disease and hospitalisation.

The vaccine, developed with Oxford University, was also shown to have an 85% efficacy against symptomatic COVID-19 in participants aged 65 years and over, which should continue to ease concerns in Europe that the shot may not be effective in older people.

This primary analysis included the accrual of 190 symptomatic cases of COVID-19 from the 32,449 trial participants, an additional 49 cases to the previously announced interim analysis. Patients were given two doses of the jab four weeks apart, with one in every three participants administered with a placebo.

The further analysis also confirmed that there were no safety concerns related to the vaccine, countering fears that the shot may cause blood clotting.

These results come after The National Institute of Allergy and Infectious Diseases (NIAID) in the US released a statement on Tuesday. They said AstraZeneca, “may have included outdated information from that [AZD1222] trial, which may have provided an incomplete view of the efficacy data.”

AstraZeneca responded later on Tuesday, explaining that the previous numbers were based on an interim analysis, with a data cut-off of February 17. The news today confirms the company’s assertion that, “preliminary assessment of the primary analysis and the results were consistent with the interim analysis.”

NIAID are yet to comment on the new primary analysis released today.

Mene Pangalos, Executive Vice President of BioPharmaceuticals R&D at AstraZeneca, said: “The primary analysis is consistent with our previously released interim analysis, and confirms that our COVID-19 vaccine is highly effective in adults, including those aged 65 years and over. 

“We look forward to filing our regulatory submission for Emergency Use Authorisation in the US and preparing for the rollout of millions of doses across America.”

Jack Goddard

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