AstraZeneca and its research partner the University of Oxford on Monday released the first photo of the large clinical trial they have conducted in the United States for their COVID-19 vaccine, concluding that it is safe and prevents 79% of diseases symptomatic.
Interim results from the 32,000-person trial showed the vaccine met Food and Drug Administration guidelines for safety and efficacy. The company said it will continue to analyze the results of the trial and will seek approval in a few weeks to begin distributing its two-dose vaccine in the United States.
It would be the fourth vaccine authorized in the United States, alongside those from Pfizer-BioNTech, Moderna and Johnson & Johnson.
Countries in Europe, which previously allowed the AstraZeneca-Oxford vaccine, have suspended its use after a number of people developed blood clots or other bleeding disorders shortly after receiving the vaccine. It has already been distributed to nearly 20 million people in Europe, UK and Asia.
Last week, the European Medicines Agency – the European version of the FDA – found the vaccine to be safe for general use, although it couldn’t rule out that the shot played a role in rare blood clots in the vessels draining the brain, called the cerebral. venous sinus thrombosis.
In the latest trial, which included volunteers from the United States, Chile, and Peru, an independent review panel looked specifically for blood clots and “found no increased risk of thrombosis or events characterized by blood clots. thrombosis among the 21,583 participants receiving at least one dose of the vaccine, ”according to a press release from the company.
There were no cases of cerebral venous sinus thrombosis in this trial.
Among participants in the new trial, 141 people have so far developed symptomatic COVID-19. None of those who received the vaccine, currently known as AZD1222, have been hospitalized or died from COVID-19, making it 100% effective against serious illnesses, the company said.
Two-thirds of the trial volunteers received the active vaccine and one-third a placebo.
There was no apparent difference in vaccine effectiveness based on ethnicity or age, the company said. The vaccine was found to be 80% effective in people 65 and older, the first time it was tested on such a large group of older people.
The trial was led by AstraZeneca and funded by the US government.
About 79% of the trial participants were white, 8% black, 4% Native American (mainly from Peru and Chile), and 4% Asian. About 22% were Hispanic.
About 20% of the volunteers were 65 and older and about 60% had medical conditions associated with an increased risk of severe COVID-19, including diabetes, heart disease or severe obesity.
The company will continue to follow trial participants for two years after their second injection to research duration of effectiveness and any safety concerns, although most problems associated with vaccines appear within the first six weeks.
The two doses were given four weeks apart, although they were given up to 12 weeks apart in previous trials and in Europe, and appear to be more effective with a longer interval.
The vaccine can be stored in the refrigerator and does not need to be frozen unless it is stored for more than six months.
A previous clinical trial of the AstraZeneca-Oxford vaccine raised questions about its effectiveness against a variant of the virus first seen in South Africa.
In a trial involving 17,000 people in the UK, South Africa and Brazil, the vaccine showed 76% effectiveness in preventing symptomatic COVID-19 after a single dose, according to a study published this month. here in The Lancet. A second booster injection, necessary for longer term protection, was given at three months and increased protection to 82%.
But in South Africa, less than half of participants were protected against symptomatic COVID-19 – which would place it below the effectiveness required for use in the United States. Still, there were no serious cases of COVID-19 or hospitalization among those vaccinated once the vaccine took full effect, around 22 days after the first dose, the study showed.
Other problems persisted in this trial, with some participants mistakenly receiving a lower dose of the vaccine, and few people over 65 included.
Obtaining both doses of the vaccine appeared to reduce transmission of the virus among these trial participants. Although vaccines are designed to protect against the disease, not all of them also prevent an infected person from transmitting the virus. This has been an open question with COVID-19 vaccines, although a growing body of evidence suggests they are slowing the spread of the disease.
No significant safety concerns were raised with this trial, although it was briefly put on hold last fall to examine a rare neurological condition that developed in one trial participant. The US test was also halted at that time to ensure safety.
The Trump administration has pre-purchased 300 million doses of the AstraZeneca-Oxford vaccine, to be provided to the American public if the vaccine is cleared for use.
A spokeswoman for AstraZeneca said the company will have around 30 million doses to Americans by the end of March and an additional 20 million by the end of April.
“We expect to be able to deliver 15 to 25 million doses per month thereafter,” wrote Abigail Bozarth, US director of external communications, in a recent email. “We are continually looking for ways to speed up. We are cautious in this estimate due to the variables involved in making a vaccine.”
Some have called on the United States, which will have enough vaccines by the end of May for every American adult, to distribute these doses of AstraZeneca-Oxford elsewhere in the world.
AstraZeneca is already planning to deliver hundreds of millions of doses of the vaccine to 142 countries, many of which are considered middle and low income.
The AstraZeneca-Oxford vaccine is made with technology similar to that of Johnson & Johnson, using a harmless virus to deliver a piece of the virus that causes COVID-19 into the body. While J&J uses a human cold virus as its delivery system, the vaccine developed at the University of Oxford and marketed by AstraZeneca relies on a chimpanzee virus, which the human immune system has never seen before.
The Pfizer-BioNTech and Moderna vaccines are based on so-called mRNA technology, which instructs cells to produce the viral particle.
All vaccines deliver the same piece of the coronavirus: the “spike” protein found on the outside of the SARS-CoV2 virus. Once the immune system sees this viral particle, it must recognize it if it is infected and attack the virus before it can take hold.
Contact Karen Weintraub at [email protected]
Patient health and safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial contributions.