AstraZeneca’s Covid-19 vaccine is safe and 79% effective in late-stage trials in the US.

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PLC’s Covid-19 vaccine was shown to be safe and 79% effective in preventing symptomatic diseases in US clinical trials involving more than 32,000 people, the British pharmacist said Monday.

The company said it will continue to analyze the data and prepare to apply for emergency authorization in the US in the coming weeks, a move that, if approved, will add another vaccine available to Americans.

The injection is already widely used outside of the US The US trials, however, reflect the largest-scale testing so far of the vaccine and could bolster confidence in its use after questions about its efficacy and serious clotting problems. of blood in a very small number of people in Europe who were shot. The US trials did not identify an increased risk of severe blood clotting.

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AstraZeneca said participants 65 and older were shown to have 80% vaccine efficacy.

Concerns about blood clotting led more than a dozen European countries, including Germany and Italy, to temporarily suspend use of the vaccine this month. Most resumed administration of the vaccine after UK and European drug regulators again endorsed the use of the injection despite rare clotting problems, which were not shown to be related to the vaccine. Regulators said they could not rule out a connection, but said the vaccine is an important weapon in preventing death and serious illness and that its benefits outweigh the potential risks.

Much depends on the global acceptance of the AstraZeneca intake, which was developed jointly with the University of Oxford and is the most widely used in many parts of the world. The US Food and Drug Administration is expected to review the trial data and can decide whether to authorize use of the vaccine starting next month.

Results from earlier trials of the injection from the UK and elsewhere were criticized for a lack of elderly volunteers, who were recruited later in the testing process for safety reasons. The UK and other countries used the vaccine in people over 55, but some countries initially held back and only implemented the vaccine in younger age groups.

The US trial involved 32,449 participants aged 18 years or older, and about 20% were 65 years or older. The vaccine was 100% effective in preventing serious illness and hospitalizations, with similar results across all ages and ethnic groups.

Results from the vaccine trial in the UK, published late last year, had an effectiveness range of 62% to 90%. That range was difficult to compare with results from the US trial of rival vaccines, one from Pfizer. Inc.

and the German BioNTech SE and another from Moderna Inc.

Both were found to be more than 90% effective in the US trials.

Europe’s top drug regulator backed AstraZeneca’s vaccine after it was suspended in several countries over concerns about blood clots. WSJ explains the stakes for a shot that has been used extensively around the world and will soon be considered for emergency use in the US Photo: Mykola Tys / SOPA Images

Independent researchers have not yet reviewed the results of the trial in the US AstraZeneca said the analysis will be submitted for publication in a peer-reviewed journal.

AstraZeneca said independent safety monitors conducted a specific review of severe blood clotting or serious thrombotic events, based on data from the trial, including a serious condition known as cerebral venous sinus thrombosis that has been reported to be associated with a very high number. small number of deaths in Europe among people who received the vaccine. The review was assisted by an independent neurologist. It did not find an increased risk of thrombosis among 21,583 participants who received at least one dose of the vaccine, AstraZeneca said.

The US AstraZeneca vaccine trial, which began recruiting volunteers in the US, Chile and Peru in August, was standardized to meet FDA guidelines, measuring the results of two doses with four weeks of difference. AstraZeneca said extending the doses, which the UK and other countries have done, could further increase the effectiveness of the vaccine.

Results from the US late stage trial provide the closest comparison between the AstraZeneca vaccine and rival injections that were the first to be adopted in the US Clinical trials showed that Pfizer and Moderna injections have an effectiveness greater than 94% against symptomatic Covid-19.


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Meanwhile, the Oxford-led trials of the AstraZeneca-Oxford vaccine last year in the UK and Brazil produced a confusing series of results, ranging from 62% to 90%, depending on dose size and timing.

Real world vaccination data, highly dependent on the UK. Since then, the mass launch has shown that a single injection is around 70% effective and highly effective in preventing deaths and hospitalizations. Those results suggested that separating the two doses by about 12 weeks helped boost immunity, resulting in about 80% effectiveness among people 70 and older, after the second injection. British researchers said the result was similar to the results of more than 70 from the Pfizer-BioNTech vaccine.

The developing world is counting heavily on the AstraZeneca-Oxford injection, with 3 billion doses promised with no profit this year. But public health experts were concerned about the complex results of the trial last year, and AstraZeneca’s prolonged tension with European officials over extreme shortages in vaccine delivery targets could cause lasting damage to the vaccine’s reputation.

Those factors and errors by AstraZeneca in its public and regulatory communications last year could affect perceptions of the vaccine in the US, some AstraZeneca experts and analysts have said.

In late February, the US licensed Johnson & Johnson’s Covid-19 vaccine for the US market, bringing a third injection to the country’s vast supply chain. That one-dose injection was found to be generally safe and 66.1% effective in protecting people from developing moderate and severe cases of Covid-19 at least 28 days after vaccination, according to a study of approximately 44,000 volunteers from 18 years or older.

British Prime Minister Boris Johnson receives the first dose of the AstraZeneca vaccine in London on Friday.


Frank Augstein / Zuma Press

Launching the vaccine in the US has faced challenges in supply and distribution. But both the production and the administration of injections have recovered in recent weeks. Now, about 2.5 million people in the US are vaccinated daily on average, up from 500,000 in early January.

But many people who want a vaccine cannot get it. AstraZeneca vaccine stocks cannot be distributed in the US until the injection is cleared by the FDA.

Last week, the Biden administration announced plans to ship 4 million doses of the AstraZeneca vaccine stored in the US to Canada in Mexico, as a loan before possible authorization. Authorities said no deal was made.

The United States said it has 7 million “releasable doses” of the AstraZeneca vaccine. In all, the United States ordered 300 million doses of the AstraZeneca-Oxford vaccine, including a contract for 200 million doses for the Department of Defense.

The United States has accelerated vaccine production to meet national goals, including fostering manufacturing partnerships among vaccine manufacturers and increasing funding to accelerate the production of ingredients and supplies.

AstraZeneca has built a global network of manufacturing partners, including the Serum Institute in India, the world’s largest vaccine manufacturer, to meet its delivery goals. Staggered approvals, production shortfalls and export battles have complicated the launch. AstraZeneca executives have said they are solving supply chain problems and plan to eventually meet their announced obligations.

Following reports of blood clotting in Europe, regulators said last week that they will add a warning to the vaccine’s use guidelines and patient information sheets, for healthcare providers and individuals who receive the injection watch for signs of rare diseases. called thromboembolic problems, including a serious brain condition that has caused a very small number of deaths in people who received the vaccine, and continued to support the injection. But regulatory officials stressed that no link was shown between the vaccine and clotting problems, which also occur naturally in the general population and in many cases from Covid-19.

Write to Jenny Strasburg at [email protected]

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