A US study of AstraZeneca’s COVID-19 vaccine showed it to be effective and did not increase the risk of rare blood clots reported in Europe, the company announced Monday.
Although the jab has been licensed in more than 50 countries, it has yet to receive a green light in the US.
The study included more than 30,000 volunteers, of whom two-thirds received the vaccine, while the rest received placebos.
AstraZeneca said in a statement that its vaccine was 79% effective in preventing symptomatic COVID-19 and 100% effective in stopping serious illness and hospitalization, although it has not yet released the full data.
The researchers said the vaccine worked for all ages, including older people, something the experts wanted better data on.
People were given two doses of the AstraZeneca vaccine four weeks apart.
“These findings reconfirm previous observed results,” said Ann Falsey of the University of Rochester School of Medicine, who helped lead the trial. “It’s exciting to see similar efficacy results in people over 65 for the first time.”
The AstraZeneca jab is a mainstay of a UN-backed project known as COVAX that aims to bring COVID-19 vaccines to the poorest countries, and has also become a key tool in European countries’ efforts to boost their slow vaccine launches.
The early findings from the US study are just one set of information that AstraZeneca must submit to the Food and Drug Administration (FDA) in order for its vaccine to be approved for use in the country.
An FDA advisory committee will publicly debate the evidence behind the injections before the agency decides whether to allow emergency use of the vaccine.
In the past, the time from when a company disclosed efficacy data to when a jab was authorized in the US was approximately one month.
Scientists hoped the US study would clear up some of the confusion about how well injections actually work, particularly in older people.
Previous research suggested that the vaccine was effective in younger populations, but there was no robust data to prove its efficacy in people over 65, who are often the most vulnerable to COVID-19.
Britain first licensed the vaccine based on partial results of tests in the UK, Brazil and South Africa, which suggested that the injections were around 70% effective.
But those results were clouded by a manufacturing error that led some participants to receive only half the dose in their first injection, a mistake the researchers did not immediately recognize.
Then came more questions about how well the vaccine protected older adults and how long to wait before the second dose.
Some European countries, including Germany, France and Belgium, initially withheld the vaccine for older adults and only reversed their decisions after new data suggested it was offering protection to older people.
AstraZeneca vaccine development was also difficult in the US Last fall, the FDA suspended the company’s study for six weeks as frustrated regulators sought information on some neurological complaints reported in Britain. Ultimately, there was no evidence that the vaccine was the culprit.
Last week, more than a dozen countries, mainly in Europe, temporarily suspended the use of the AstraZeneca vaccine after reports that it was linked to rare blood clots, even as international health agencies insisted that the benefits of the vaccine outweigh the risks.
On Thursday, the European Medicines Agency concluded after an 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 clots. He recommended adding a warning about these cases to the vaccine package insert.
It is not uncommon for such rare problems to emerge as vaccines are implemented, as trials typically test tens of thousands of people, and some problems are only seen once the jab is used in millions of people.
France, Germany, Italy and other countries subsequently resumed use of the vaccines on Friday, and high-level politicians rolled up their sleeves to show that the vaccine was safe.
AstraZeneca said it will continue to analyze the US data before submitting it to the FDA in the coming weeks. He said the data will also be published soon in a peer-reviewed journal.
The AstraZeneca injection is what scientists call a “viral vector” vaccine. The doses are made with a harmless virus, a cold virus that normally infects chimpanzees, that acts like a Trojan horse to transport the genetic material from the coronavirus spike protein to the body which in turn produces a harmless protein. This prepares the immune system to fight if the real virus appears.
Two other companies, China’s Johnson & Johnson and CanSino Biologics, make COVID-19 vaccines using the same technology but using different cold viruses.
George is Digismak’s reported cum editor with 13 years of experience in Journalism