LONDON (AP) – AstraZeneca’s COVID-19 vaccine provided strong protection against disease and complete protection against hospitalization and death in all age groups at the late stage of a US study, the company announced Monday.
AstraZeneca said its experts have also not identified any safety concerns related to the vaccine, including a rare blood clot identified in Europe. Scientists found no increased risk of blood clots in the more than 20,000 people who received at least one dose of the AstraZeneca injection.
Although AstraZeneca’s vaccine has been approved in more than 50 countries, it has not yet received a green light in the US. The US study involved more than 30,000 volunteers, two-thirds of whom received the vaccine, with the rest receiving fake injections.
In a statement, AstraZeneca said the COVID-19 vaccine was 79% effective in preventing symptomatic COVID and 100% effective in stopping serious illness and hospitalization. Researchers said the vaccine was effective for all ages, including older people – which previous studies in other countries had failed to determine.
“These findings confirm the results previously observed,” said Ann Falsey of the University of Rochester School of Medicine, who helped lead the trial. “It’s exciting to see similar efficacy results for the first time in people over 65 years old.”
Julian Tang, a virologist at the University of Leicester who had no affiliation with the study, described it as “good news” for the AstraZeneca vaccine.
The previous studies in the UK, Brazil and South Africa had a more variable and inconsistent design and it was thought that the US FDA would never approve the use of the AZ vaccine on this basis, but now the US clinical trial has confirmed the efficacy of this vaccine in their own clinical trials, ”he said.
The US study’s initial findings are just one set of information that AstraZeneca must submit to the Food and Drug Administration. An FDA advisory committee will publicly debate the evidence behind the shots before the agency decides whether to allow emergency use of the vaccine.
Scientists have been awaiting the results of the US study in hopes that it will clear up some of the confusion about how well the shots really work.
Britain first approved the vaccine based on partial results from tests in the UK, Brazil and South Africa that suggested the injections were about 70% effective. But those results were clouded by a manufacturing flaw that caused some participants to receive only half a dose in their first shot – a flaw that the researchers didn’t immediately recognize.
Then more questions arose about how well the vaccine protected older adults and how long to wait for the second dose. Some European countries, including Germany, France and Belgium, initially held the shot for older adults and only reversed their decisions after new data suggested it offers seniors protection.
AstraZeneca’s vaccine development was also slow in the US. Last fall, the Food and Drug Administration suspended the company’s investigation of 30,000 Americans for an unusual six weeks as frustrated regulators sought information about some of the neurological complaints reported in Britain; in the end, there was no evidence that the vaccine was to blame.
Last week, more than a dozen countries, mainly in Europe, temporarily discontinued their use of the AstraZeneca injection after reports that it was linked to blood clots. On Thursday, the European Medicines Agency concluded after investigation that the vaccine did not increase the overall risk of blood clots, but could not rule out that it was linked to two very rare types of blood clots.
France, Germany, Italy and other countries then resumed their use of the shot on Friday, with senior politicians rolling up their sleeves to show the vaccine was safe.
AstraZeneca said it would continue to analyze US data in preparation for submission to the FDA in the coming weeks. It said the data would also be published in a peer-reviewed journal soon.
The AstraZeneca vaccine is what scientists call a “viral vector” vaccine. The recordings were made with a harmless virus, a cold virus that normally infects chimpanzees. It acts like a Trojan horse to deliver the genetic material of the spike protein into the body, which in turn produces a harmless protein. That stimulates the immune system to fight when the real virus comes along.
Two other companies, Johnson & Johnson and CanSino Biologics of China, make COVID-19 vaccines with the same technology but different cold viruses.
The AstraZeneca injection has become an important tool in European countries’ efforts to boost their slow vaccine launches. It is also a pillar of a UN-backed project known as COVAX that aims to bring COVID-19 vaccines to poorer countries.
Neergaard reported from Washington.
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