Early data suggest AstraZeneca's COVID-19 vaccine effective against Brazil variant: report

According to a source familiar with the matter, preliminary study findings indicate that AstraZeneca's coronavirus vaccine AZD1222 is effective against the P.1 variant of SARS-CoV-2 first identified in Brazil. The source did not provide exact efficacy of the vaccine against the P.1 strain, but said full results from the study should be released soon, possibly this month.

The vaccine, which is co-developed with the University of Oxford, is authorised for emergency use in several countries, including the UK and those in the EU, among others. A combined interim analysis released last November from a Phase II/III trial in the UK and a Phase III study in Brazil showed that AZD1222 had an average efficacy of 70%. Subsequent analyses indicated it was nearly as effective against symptomatic COVID-19 caused by the so-called UK variant, also known as B.1.1.7, but showed minimal protection against mild-to-moderate illness from the B.1.351 strain predominant in South Africa. The finding prompted South Africa to pause use of the vaccine in that country.

AstraZeneca has said it is working on updating AZD1222 to target new SARS-CoV-2 variants, with hopes of having a new version ready by the fall. However, the source who disclosed the latest data suggested that the vaccine may not need to be modified in order to protect against the P.1 strain.

Brazilian research institute Fiocruz, which sent the samples that formed the basis of the study, said it did not have other information about it as the work was being led by AstraZeneca and its partners at Oxford. Representatives for AstraZeneca and the university did not immediately respond to requests for comment. Meanwhile, the news comes as a small-sample laboratory study suggests Sinovac's COVID-19 vaccine CoronaVac may not work effectively against the P.1 variant.

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