A third vaccine for Covid-19 is hurtling toward the finish line.
AstraZeneca and Oxford University are preparing to request emergency approvals for their vaccine candidate based on promising interim results of clinical trials in the United Kingdom and Brazil.
It’s the third vaccine candidate to emerge over the last few weeks, fueling hopes that an end to the Covid-19 pandemic may be in sight. The Dow Jones Industrial Average rose more than 1% on the news. The earlier candidates were unveiled by Moderna Therapeutics and Pfizer/BioNTech, which has applied for emergency use authorization from the U.S. Food and Drug Administration.
AstraZeneca and Oxford studied two dosing regimens for their vaccine, known as AZD1222, and pooled results from two trials, a Phase II/III in the United Kingdom and a Phase III in Brazil.
The first dosing regimen, involving half a dose followed by a full dose about a month later, had an efficacy rating of 90%. The second, involving two full doses a month apart, showed an efficacy of about 62%.
Their combined rate was 70%, with no serious safety events related to the vaccine, according to AstraZeneca. The London-based drug maker briefly paused its studies in September due to an undisclosed adverse event.
The FDA guidelines for a Covid-19 vaccine set an efficacy floor of 50%. Early results are raising the bar, though none have yet been peer reviewed. Pfizer/BioNTech and Moderna are showing efficacy ratings of around 95%.
AstraZeneca and Oxford are continuing to gather more data to refine their efficacy ratings and determine how long protection lasts. Clinical trials so far have reached more than 23,000 people but are expected to reach up to 60,000 and extend into the U.S., Japan, Russia, South Africa and Kenya, among other countries in Europe, Asia and Latin America.
The partners sounded an optimistic note in unveiling the interim results, which were confirmed by the independent Data Safety Monitoring Board.
“Today marks an important milestone in our fight against the pandemic,” AstraZeneca CEO Pascal Soirot said in a statement. “This vaccine’s efficacy and safety confirm that it will be highly effective against Covid-19 and will have an immediate impact on this public health emergency.”
The vaccine primes the immune system to attack Covid-19 by using a replication-deficient chimpanzee viral vector that is based on a weakened version of a common cold virus, one that can infect chimpanzees and contains genetic material of the Covid-19 spike protein.
In addition to government approvals, AstraZeneca and Oxford are seeking an emergency use listing from the World Health Organization, which they hope will speed up the vaccine’s availability in low-income countries.
Doses can be stored, transported and handled at standard refrigerator temperatures of between 2 and 8 degrees Celsius or 36 to 46 degrees Fahrenheit, suggesting that the vaccine will not face additional logistical challenges. Pfizer’s vaccine must be kept at extremely low temperatures.
London-based AstraZeneca expects to produce up to 3 billion doses in 2021. New York-based Pfizer is aiming for 1.3 billion doses, with the first 50 million coming in December. Based in Cambridge, Massachusetts, Moderna has a goal of between 500 million and 1 billion, with 20 million ready by the end of this year.
An FDA advisory panel is scheduled to discuss Pfizer’s emergency use application on Dec. 10.
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