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The efficacy of the AstraZeneca vaccine depends on the dose (Photo: REUTERS / Dado Ruvic)
HB publishes a translation of New York Times material on the world’s third effective vaccine to help overcome the COVID-19 pandemic.
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A smaller dose is more effective
Pharmaceutical AstraZeneca announced on November 23 that preliminary analyzes from its late-stage clinical trials in the UK and Brazil indicate that its vaccine is 90% effective when given in one dose and 62% when given in another dose. These are encouraging results for a vaccine that should go a long way toward curbing the global pandemic that has killed more than 1.3 million people.
The average efficacy of the two dosage regimens is 70%. The company said its vaccine can be stored for at least six months in a standard refrigerator and does not require the harsh refrigeration required for other vaccines whose manufacturers have previously claimed to be effective. This makes it easy to distribute a vaccine that is also cheaper and easier to manufacture than some of its competitors.
In the dosing regimen that worked best, study participants received half the vaccine dose first and the full dose one month later. The vaccine was less effective with a full dose first and a full dose a month later. If regulatory agencies around the world approve a seemingly more effective regimen, it could allow more people to get vaccinated at a time when vaccines are still in short supply.
The British-Swedish company, which was developing the vaccine with the University of Oxford, is the third major developer to announce encouraging preliminary results this month. The first were Pfizer and Moderna, who said that their vaccines were 95% effective in the last phase of their research.
Cheaper sometimes
AstraZeneca’s findings could significantly bolster global efforts to produce enough vaccine to build herd immunity. The $ 3- $ 4 injection price is notably lower than other potential vaccines (Moderna has priced a dose of its vaccine between $ 25 and $ 37, while a two-shot course of the Pfizer vaccine will cost around $ 40 – Ed.). And AstraZeneca is committed to making it affordable until at least July 2021, and forever in the poorest countries.
The vaccine can also be produced relatively easily in large quantities. AstraZeneca said it plans to start shipping the vaccine later this year and produce up to 3 billion doses next year.
Scientists say they have not identified any «serious vaccine-related safety events, ”which is encouraging. The vaccine became the focus of global attention after AstraZeneca temporarily suspended its trials in September to investigate potential safety concerns after a participant from the UK developed a neurological disease.
Oxford and AstraZeneca said they would pass the data on to regulators in the UK, Europe and Brazil and request permission for emergency distribution of the vaccine there, as well as begin discussions about their data with US regulators.
How the sick were viewed
The company said its preliminary analysis was based on 131 cases of coronavirus identified among study participants at least two weeks after they received a second vaccine. In a UK trial, researchers counted the number of infections weekly by taking swabs from trial participants. This screening method has likely identified more infections than the trials conducted by Moderna and Pfizer, which evaluated people who developed symptoms and may not have been able to detect asymptomatic cases. Different approaches to counting the number of infected people can make it difficult to compare the effectiveness of different vaccines.
Oxford and AstraZeneca also said that none of the vaccinated trial participants who became ill required hospitalization. In addition, the scientists observed a decrease in the number of asymptomatic infections, which is why they suggested that the vaccine could reduce the number of transmissions.
Prospects for a new vaccine
The Oxford scientists said they are still trying to understand why the vaccine was more effective when the first dose was lower. The first dose should boost your immune system and the second should stimulate your response. While it seemed counterintuitive that a lower first dose would be more effective, the researchers said such a strategy could more closely mimic what happens during an actual infection.
The half-dose regimen is not currently being tested in the latest phase of AstraZeneca trials in the US, but the company said it will work with the US Food and Drug Administration to add it as soon as possible. He promised to share his findings with the FDA this week and will begin discussions on whether to formally submit the results for review and approval. Regulators in the UK are already conducting an ongoing review of vaccines.
«Today marks an important milestone in our fight against the pandemic. The efficacy and safety of this vaccine confirms that it will be very effective against COVID-19 and will have an immediate impact on this public health emergency, ”said Pascal Sorio, CEO of AstraZeneca.
Professor Andrew Pollard, Principal Investigator of the Oxford Vaccine Trials, said that «these results show that we have an effective vaccine that will save many lives. “
Pam Chen, executive vice president of AstraZeneca, said on Nov. 23 that if the company gets regulatory approval, it expects 4 million doses to be available in the UK by the end of the year.
The company also said it will have at least 300 million doses of vaccine ready for distribution globally by the end of the first quarter of 2021.
However, even without delay, there is still a long way to go until the vaccine is widely available. Regulatory authorities must evaluate the study data and decide whether to approve the vaccine. AstraZeneca must increase production and work with government officials to distribute it. It is expected that in the first weeks and months after the vaccine is approved, it will be available only to the highest priority groups, probably healthcare workers, and only then to other vulnerable groups.
Pam Chen said the vaccine’s half-dose regimen would not complicate the supply chain too much.
The Food and Drug Administration (FDA) said it expects the COVID-19 vaccine to prevent or reduce the severity of the disease in at least half of those vaccinated. This is similar to the effectiveness of the seasonal flu vaccine in most years. Preliminary test results from other vaccine manufacturers, including Johnson & Johnson, are expected soon.
Simple storage conditions
The AstraZeneca vaccine is expected to have relatively simple storage requirements, which will be an advantage in distribution. Moderna vaccine can be stored for up to a month in conventional refrigerators. Pfizer vaccine can be stored for up to five days in conventional refrigerators or in special refrigerators for up to 15 days, but longer storage requires ultra-low temperatures.
«Our goal is to make the vaccine available everywhere. I think we did it, ”said Professor Pollard.
The data, released Nov. 23, comes from AstraZeneca’s phase 2/3 clinical trials in the UK and a phase 3 clinical trial in Brazil. The participants were randomized: half received the coronavirus vaccine, the other half received the meningitis vaccine, and after about a month, the trial participants were vaccinated again.
As of early November, AstraZeneca had a total of 23,000 participants in the mid and late stages of testing in the UK, Brazil, South Africa and the United States. The results of the company’s investigation in the United States are not expected to appear until next year. This test, in which 30,000 people will participate, slowed down due to a security break, which lasted for more than a month.
Vaccine development technology
The AstraZeneca vaccine is based on an adenovirus found in chimpanzees that has been genetically altered to harmlessly mimic the coronavirus and elicit an immune response. A vaccine created with this technology has never received approval. But this approach has been studied before. In particular, during a small study of an experimental vaccine against the virus that causes respiratory cider from the Middle East (MERS), in 2018. This virus is close to SARS-CoV-2, the new coronavirus that causes COVID-19.
So when COVID-19 emerged, the Jenner Oxford Institute team of scientists who led the work on similar coronaviruses had an advantage. After the SARS-CoV-2 genetic code was published in early January, the Oxford team rushed to adapt their platform to the novel coronavirus and begin animal testing.
They also needed a development and manufacturing partner, and in April they became AstraZeneca. That same month, security testing began in the UK.
In May, the US Department of Health and Human Services pledged up to $ 1.2 billion to fund the development and production of the AstraZeneca vaccine and reserve at least 300 million doses if it proves effective. Alex Azar, secretary of the US Department of Health and Human Services, called the deal «milestone ”in Operation Accelerate, the United States government program to accelerate the introduction of COVID-19 vaccines.
AstraZeneca has reached agreements to supply doses of its vaccine, after receiving approval, to other wealthy countries, including the UK and other countries in Europe, as well as to low- and middle-income countries.
The company promised not to benefit from the vaccine during the pandemic, but in one of its contracts it suggested that it could announce the end of the pandemic in July 2021, The Financial Times wrote.
NV translation
