AstraZeneca’s Covid-19 vaccine is safe, 79% effective in late-stage US studies

The shot is already in widespread use outside of the US. However, the US studies reflect the largest testing 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 who have received the shot. The US studies have not identified an increased risk of serious blood clotting.

AstraZeneca said participants 65 and older had an 80% vaccine effectiveness.

Concerns about blood clotting have caused more than a dozen European countries, including Germany and Italy, to temporarily stop using the vaccine this month. Most resumed giving the vaccine after European and UK drug regulators re-approved the use of the injection, despite the rare clotting problems, which had not been proven to be related to the vaccine. The regulators said they couldn’t rule out an association, but said the vaccine is an important weapon in preventing death and serious illness and that the benefits outweigh the potential risks.

Much depends on the global acceptance of the AstraZeneca shot, which was co-developed with the University of Oxford and is most commonly used in many parts of the world. The U.S. Food and Drug Administration is expected to review the study data and decide whether to use the vaccine as early as next month.

Previous trial results of the shot from the UK and elsewhere have been criticized for the lack of older volunteers, who were later recruited into the trial process for safety reasons. The UK and other countries used the vaccine in people over 55, but some countries initially withheld and only used the injection in younger age groups.

The US study involved 32,449 participants 18 years of age and older, and about 20% were 65 years of age or older. The effectiveness of the vaccine was 100% in the prevention of serious illness and hospital admissions, with comparable results for all age and ethnic groups.

The UK research results of the vaccine, released late last year, showed a range of effectiveness, between 62% and 90%. That range was difficult to compare with US research results of competing 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 US studies.

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

AstraZeneca said independent safety monitors conducted a specific study of serious blood clotting or serious thrombotic events, based on the study data, including a serious condition known as cerebral venous sinus thrombosis that has been reported to be associated with a very small number of deaths in Europe among people who have received the vaccine. The assessment 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 US AstraZeneca vaccine trial, which began recruiting volunteers in the US, Chile and Peru in August, was standardized to meet FDA guidelines, measuring results from two doses four weeks apart. AstraZeneca said the dose stretching – which the UK and other countries have done – could further increase the effectiveness of the vaccine.

The results of the late-stage US tests provide the best comparison to date between the AstraZeneca vaccine and rival injections first used in the US Clinical studies showed that the Pfizer and Moderna injections exceed 94% were effective against symptomatic Covid-19.

Oxford-led trials of the AstraZeneca-Oxford vaccine last year in the UK and Brazil, meanwhile, yielded a confusing array of results, ranging from 62% to 90%, depending on dose size and time point.

Real-world vaccination data, highly dependent on that of the UK. massive rollout, has since shown that a single shot is about 70% effective and very effective at preventing death and hospital admissions. Those results suggested that separating the two doses by about 12 weeks helped boost immunity, resulting in about 80% effectiveness in people 70 years of age or older, after the second injection. British researchers said the result was comparable to the more than 70 results from the Pfizer-BioNTech vaccine.

The developing world is counting heavily on the AstraZeneca-Oxford shot, with 3 billion non-profit doses promised this year. But public health experts were concerned about last year’s complex research results and AstraZeneca’s long-standing tension with European officials over extreme shortcomings in vaccine delivery targets could cause lasting damage to the vaccine’s reputation.

Those factors and missteps that AstraZeneca made in its public and regulatory communications last year could affect the perception of the vaccine in the US, some AstraZeneca experts and analysts have said.

In late February, the US approved Johnson & Johnson’s Covid-19 vaccine for the US market, putting a third shot in the country’s extensive supply chain. That single-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, based on a study of approximately 44,000 volunteers aged 18 years and older.

The rollout of vaccinations in the US has faced supply and distribution challenges. But both the production and administration of shots has picked up again in recent weeks. Today, an average of 2.5 million people in the US are vaccinated daily, up from about 500,000 in early January.

But many people who want a vaccine cannot get one. Stocks of the AstraZeneca vaccine cannot be distributed in the US until inclusion is approved by the FDA.

Last week, the Biden administration announced plans to send 4 million doses of the stored AstraZeneca vaccine in the US to Canada in Mexico as a loan ahead of a potential approval. Officials said no deal had been struck.

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

The US has accelerated vaccine production to meet its domestic targets, including by promoting manufacturing partnerships between vaccine makers 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 producer, to meet its supply targets. Staggered approvals, production shortages and export battles have made the rollout difficult. AstraZeneca’s executives have said they are resolving supply chain issues and plan to eventually meet announced commitments.

Following the blood clotting reports in Europe, regulators there said last week that they will add a warning to the vaccine’s guidelines for use and patient information sheets for health care providers and people receiving the injection to be on the lookout for signs of rare sothromboembolic problems – including a serious brain disease that has led to a very small number of deaths in people who received the vaccine – and the injection has continued to support. But regulatory officials stressed that no link had been shown between the vaccine and clotting problems, which also occur naturally in the general population and in many cases with Covid-19.

Write to Jenny Strasburg at [email protected]