AstraZeneca’s Covid-19 vaccine is safe, with 79% efficacy in US end-stage trials

The shot is already widely used outside the United States. U.S. trials, however, reflect the largest evidence of the vaccine to date and could bolster confidence in its use after questions about its effectiveness and serious blood clotting problems in a very small number of people. in Europe that received the shot. U.S. trials did not identify an increased risk of severe blood clotting.

AstraZeneca said participants 65 years of age or older were shown to have a vaccination effectiveness of 80%.

Concerns about blood clotting caused more than a dozen European countries, including Germany and Italy, to temporarily stop using the vaccine this month. Most resumed administration of the vaccine after European and British drug regulators again endorsed the use of the shot, 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.

It is based on the global acceptance of the AstraZeneca feature, which was developed in conjunction with Oxford University and is the most widely used in many parts of the world. The U.S. Food and Drug Administration is expected to review the trial data and decide whether to authorize the vaccine for use next month.

Previous results of trials from the UK and elsewhere were criticized for the lack of senior volunteers, who were recruited later in the process for safety reasons. The United Kingdom and other countries used the vaccine in people over 55, but some countries initially slowed down and only deployed the shot in younger age groups.

The American trial included 32,449 participants 18 years of age and older and approximately 20% were 65 years of age or older. The effectiveness of the vaccine was 100% in the prevention of serious diseases and hospitalizations, with similar results in all age and ethnic groups.

The results of the British vaccine trials, published late last year, showed a range of efficacy, between 62% and 90%. This range was difficult to compare with the results of US trials of rival vaccines, one of Pfizer Inc.

and the German BioNTech SE and another from Moderna Inc.

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

The results of the trials in the United States have not yet been reviewed by independent researchers. AstraZeneca said the analysis will be presented for publication in a peer-reviewed journal.

AstraZeneca said independent safety monitors performed a specific review of severe blood clotting or severe thrombotic events, based on trial data, including a serious condition known as cerebral venous sinus thrombosis that has been linked to a very small number of deaths in Europe among people who received the vaccine. The review was assisted by an independent neurologist. It found no increased risk of thrombosis among 21,583 participants who received at least one dose of the vaccine, AstraZeneca said.

The trial of the AstraZeneca vaccine in the United States, which began hiring volunteers in the United States, Chile and Peru in August, was normalized to meet FDA guidelines, measuring the results of two separate doses at four weeks. . AstraZeneca said stretching doses – which the UK and other countries have done – could further increase the effectiveness of the vaccine.

The results of U.S. final-stage trials offer the closest comparison to date between the AstraZeneca vaccine and rival shots that were the first to be adopted in U.S. clinical trials that showed Pfizer shots and Modern were more than 94% effective against symptomatic Covid-19.

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

Real-world vaccination data, which depend heavily on the UK. Mass deployment, since then, has shown that a single shot is about 70% effective and highly effective in preventing deaths and hospitalizations. These results suggested that separating the two doses in about 12 weeks helped increase immunity, resulting in 80% efficacy among people 70 years or older, after the second shot. British researchers said the result was similar to the results of more than 70 years of the Pfizer-BioNTech vaccine.

The developing world largely has the AstraZeneca-Oxford feature, with 3 billion doses promised without benefits this year. But public health experts have been concerned about the complex results of trials last year and AstraZeneca’s prolonged tension with European officials over extreme deficiencies in vaccine delivery targets could hurt the vaccine’s reputation.

These factors and missteps by AstraZeneca in its public and regulatory communications last year could affect vaccine perceptions in the United States, according to some AstraZeneca experts and analysts.

In late February, the United States authorized Johnson & Johnson’s Covid-19 vaccine for the U.S. market, and introduced a third shot to the country’s vast supply chain. It was found that this one-dose shot was generally safe and that 66.1% was effective in protecting people against the development of moderate and severe cases of Covid-19 at least 28 days after vaccination, according to a study by about 44,000 volunteers aged 18 or over.

The implementation of vaccination in the United States has faced challenges in supply and distribution. But both production and plan management have increased in recent weeks. Now, about 2.5 million people in the U.S. are vaccinated daily on average, up from 500,000 in early January.

But many people who want a vaccine can’t get it. AstraZeneca vaccine depots cannot be distributed in the United States until authorization to take is obtained from the FDA.

Last week, the Biden administration announced plans to ship 4 million doses of the AstraZeneca vaccine stored in the United States to Canada in Mexico, as a loan before possible clearance. Officials said no deal was finalized.

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

The United States has rapidly pursued vaccine production to meet national goals, including encouraging manufacturing partnerships between vaccine manufacturers and increasing funding to accelerate the production of ingredients and supplies.

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

Following reports of blood clotting in Europe, regulators said last week that they would add a warning to the guidelines for use and patient information sheets for the vaccine, for healthcare providers and for to people who receive the vaccine, so that they are looking for signs of rarity. called thromboembolic problems — including a severe brain condition that has caused a very small number of deaths in people who received the vaccine — and continued to support the shot. 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 Covid-19.

Write to Jenny Strasburg to [email protected]