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Drugmaker AstraZeneca announced on Monday that an early analysis of its late stage clinical trials in Britain and Brazil showed its coronavirus vaccine to be 90% effective when given in a single dosing schedule , but only 62% effective in a different pattern – encouraging, if complicated, the results of a vaccine that is expected to be relied upon widely across the world to help curb a pandemic that killed more than 1.3 million people.
On average, the vaccine was 70% effective on both dosing plans. The company said its vaccine could be stored for at least six months in a standard refrigerator, rather than under the intense cooling required by other major coronavirus vaccines, making it easier to distribute a vaccine that is also less expensive and easier to produce than some of its competitors. .
In the dosing plan that worked best, study participants received half a dose of the vaccine, and then, a month later, a full dose. The vaccine was less effective when they received a standard full dose in advance, followed a month later by another full dose. If the seemingly most effective regimen is the one ultimately cleared by regulators around the world, it could allow more people to get vaccinated at a time when vaccines are scarce.
The Anglo-Swedish company, which developed the vaccine with the University of Oxford, this month became the third major vaccine developer to report encouraging first results, after Pfizer and Moderna, both of which said their vaccines were about 95% effective at the end. -stage studies.
AstraZeneca’s findings could dramatically bolster the global effort to produce enough vaccines to create immunity in the population: the vaccine’s price, at $ 3-4, is a fraction of that of some other potential vaccines, and AstraZeneca has pledged to make it available at a cost of around the world until at least July 2021 and in the poorest countries in perpetuity. The vaccine can also be made in massive quantities relatively easily; AstraZeneca said it plans to start supplying the vaccine by the end of this year and manufacture up to 3 billion doses next year.
Scientists said they had not identified any “serious vaccine-related safety events,” a reassuring sign. The vaccine had come under global scrutiny after AstraZeneca temporarily suspended trials in September to investigate potential safety concerns after a British participant developed a neurological disease.
Shares rose in European markets after the announcement and Wall Street futures rose. But AstraZeneca shares slipped 1.5%.
Oxford and AstraZeneca said they would submit the data to British, European and Brazilian regulators and seek emergency clearance to begin distributing the vaccine there, and begin discussions about its data with regulators in the United States.
The company said its first scans were based on 131 cases of the coronavirus that presented among participants at least two weeks after receiving their second injection. In the UK trial, researchers counted infections by swabbing participants every week. This detection method was likely to have revealed more infections than trials conducted by Moderna and Pfizer, which tested people who developed symptoms and may not have found asymptomatic cases. Different approaches to counting infections may make it more difficult to compare the effectiveness of different vaccines.
Oxford and AstraZeneca also said that none of the vaccinated people who developed the disease needed hospitalization and that scientists had seen a reduction in asymptomatic infections, suggesting the vaccine may reduce transmission.
Oxford scientists said they were still trying to figure out why the vaccine was more effective at a smaller first dose. The first dose is supposed to stimulate the immune system, while the second is supposed to stimulate its response. While it seems counterintuitive that a smaller first dose is more effective, they said this strategy could more closely mimic what happens with an actual infection.
The half-dose regimen is currently not being tested in AstraZeneca’s advanced trial in the United States, but the company has said it will work with the United States Food and Drug Administration for the add as quickly as possible. He said he would share his data with the FDA this week and start discussions on whether he would officially submit the results for review and clearance. British regulators have already carried out a so-called continuous review of the vaccine.
“Today marks an important step in our fight against the pandemic,” said AstraZeneca CEO Pascal Soriot. “The efficacy and safety of this vaccine confirm that it will be very effective against Covid-19 and will have an immediate impact on this public health emergency.”
Professor Andrew Pollard, chief researcher of the Oxford vaccine trial, said that “these results show that we have an effective vaccine that will save many lives.”
Pam Cheng, executive vice president of AstraZeneca, said on Monday that if the company receives regulatory approval, it expects to have 4 million doses available in Britain by the end of the year. Globally, by the end of the first quarter of 2021, the company said it would have at least 300 million doses of finished vaccine ready for distribution.
Even without delay, however, the vaccine is still far from widely available. Regulators must assess the study data and decide whether or not to authorize the vaccine. AstraZeneca needs to ramp up production and work with government officials to roll out the doses. And in the first weeks and months after the vaccine is authorized, it should only be available to the highest priority groups, probably health workers first, followed by other vulnerable groups.
Ms. Cheng said the regimen involving half a dose would not significantly complicate the supply chain.
The FDA has said it expects a Covid-19 vaccine to prevent the disease or decrease its severity in at least half of those vaccinated. This is similar to the effectiveness of seasonal influenza vaccines in most years. Further interim findings from other major vaccine makers, including Johnson & Johnson, are expected soon.
AstraZeneca’s vaccine is expected to come with relatively straightforward storage requirements, which would be a plus once it is deployed. Moderna vaccine can be stored for up to a month at the temperature of a regular refrigerator. Pfizers can be stored for up to five days in conventional refrigerators, or in special coolers for up to 15 days, but otherwise require ultra-cold storage.
“Our goal is to make sure that we can have a vaccine accessible everywhere,” Professor Pollard said. “I think we managed to do it.”
The data released on Monday comes from AstraZeneca’s Phase 2/3 clinical trial in Britain and its Phase 3 clinical trial in Brazil. Participants were randomly assigned to receive either the coronavirus vaccine or a meningitis vaccine as a control, followed by a booster about a month later.
At the start of November, AstraZeneca had a total of 23,000 participants in mid-to-late stage trials in Britain, Brazil, South Africa and the United States. The results of his study in the United States should not be available until next year. The trial, which aims to recruit 30,000 participants, was slowed down by the security break that lasted more than a month.
AstraZeneca’s vaccine is designed to genetically modify an adenovirus found in chimpanzees to harmlessly mimic the coronavirus and elicit an immune response. A vaccine deploying this technology has never been approved. But the approach has already been studied, notably in a small 2018 study on an experimental vaccine against the virus responsible for Middle East respiratory syndrome, or MERS. This virus is linked to SARS-CoV-2, the new coronavirus responsible for Covid-19.
So when Covid-19 emerged, the team of scientists at the Jenner Institute in Oxford who had led the work on similar coronaviruses had a head start. After the genetic code for SARS-CoV-2 was released in early January, the Oxford team rushed to adapt their platform to the new coronavirus and begin animal testing.
They also needed a development and manufacturing partner and found one in April at AstraZeneca. Safety tests in Britain began the same month.
In May, the US Department of Health and Human Services pledged up to $ 1.2 billion to help fund AstraZeneca’s development and manufacture of the vaccine and secure at least 300 million doses if it s was effective. Alex M. Azar II, secretary of the Department of Health and Human Services, called the agreement a “major milestone” in the work of Operation Warp Speed, the US government program to speed up Covid-19 vaccines .
AstraZeneca has made deals to deliver doses of its vaccine, once licensed, to other wealthy countries, including Britain and other countries in Europe, as well as low and middle-income countries.
AstraZeneca has pledged not to take advantage of the vaccine during the pandemic, but it has suggested in one of its contracts that it may decide to declare the pandemic over as early as July 2021, the Financial Times reported.
Jenny Gross contributed reporting.
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