AstraZeneca Says COVID-19 Vaccine Candidate Shows 70% Efficacy

AstraZeneca announced that a combined interim analysis of late-stage studies showed that the COVID-19 candidate vaccine AZD1222 had an average efficacy of 70%, increasing to 90% for a regimen that included initial immunization with a half dose. The pooled data come from the COV002 phase 2/3 trial in the UK and the COV003 phase 3 study in Brazil.

According to AstraZeneca, the interim analysis included 11,636 participants and was based on a total of 131 cases of COVID-19, with the BBC reporting that there were 30 cases in people who received AZD1222. The company noted that the studies met their primary endpoint with an independent data safety monitoring board determining that the analysis showed protection from COVID-19 occurring 14 days or more after receiving two doses of the vaccine. In addition, there were no hospitalizations or severe cases of the disease reported in subjects receiving AZD1222.

Half dose upfront more effective

Further results showed that in 2741 people who received a half dose of AZD1222 followed by a full dose at least one month later, the efficacy of the vaccine was 90%. Meanwhile, another dosing regimen tested in 8895 participants showed 62% efficacy when given as two full doses at least 1 month apart. AstraZeneca added that AZD1222 was well tolerated across both dosing regimens.

Andrew Pollard, chief investigator of the Oxford Vaccine Trial, said “we’ve found that one of our dosing regimens may be around 90% effective and if this dosing regime is used, more people could be vaccinated with planned vaccine supply.” Although researchers do not know exactly why the half dose as an initial immunization proved more effective, Pollard noted “there are some examples where changing the way you prime the immune system, can result in a better response.”

Pollard added that “those who got that regimen with higher protection, there’s a suggestion that it was also able to reduce asymptomatic infection. If that’s right, that means that we might be able to hold the virus in its tracks and stop it from transmitting between people.”

Regulatory discussions up next

AstraZeneca indicated that it will now prepare submission of the data to regulatory authorities, whilst it will seek an emergency-use listing from the World Health Organization allowing for accelerated availability in low-income countries. The drugmaker added that the full analysis of the interim results will be submitted for publication in a peer-reviewed journal.

The COV002 study includes 12,390 participants aged 18 years or over, who are healthy or have medically stable chronic diseases and are at increased risk for being exposed to the SARS-CoV-2 virus, while the COV003 trial has enrolled 10,300 similar subjects. In the COV002 study, people are randomized to receive one or two intramuscular doses of a half dose or full dose of AZD1222 or comparator, meningococcal vaccine MenACWY, while in the COV003 trial, subjects are randomized to receive two intramuscular doses of a full dose of AstraZeneca’s vaccine or MenACWY as first dose and a saline placebo as second dose.

Clinical studies of AZD1222 are also being conducted in the US, Japan, Russia, South Africa, Kenya and Latin America, with planned trials in other European and Asian countries, which will include a total of up 60,000 participants globally.

“Rapid progress” on manufacturing

AstraZeneca said that it is “making rapid progress” on manufacturing AZD1222 with operations executive Pam Cheng noting that the company expects to have 200 million doses by the end of the year, with 700 million doses ready by the end of the first quarter of 2021. The drugmaker added that it aims to have a capacity of up to 3 billion doses of the vaccine in 2021 on a rolling basis. Unlike mRNA vaccines being developed by Moderna and a partnership between Pfizer and BioNTech that require very cold temperatures for storage, AstraZeneca suggested that AZD1222 “can be stored, transported and handled at normal refrigerated conditions for at least six months and administered within existing healthcare settings.”

CEO Pascal Soriot commented “the vaccine’s simple supply chain and our no-profit pledge and commitment to broad, equitable and timely access means it will be affordable and globally available, supplying hundreds of millions of doses on approval.” AZD1222, which was co-invented by the University of Oxford and its spin-out company Vaccitech, uses a replication-deficient chimpanzee viral vector and contains the genetic material of the SARS-CoV-2 virus spike protein.