AstraZeneca’s Covid-19 vaccine is safe, 79% effective in end-stage tests in the USA

The injection is already widely used outside the United States. American tests, however, reflect the larger-scale tests of the vaccine and may increase 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 been shot. Tests in the USA did not identify an increased risk of severe blood clotting.

AstraZeneca said that participants aged 65 and over have shown the vaccine to be 80% effective.

Concerns about blood clotting have prompted more than a dozen European countries, including Germany and Italy, to temporarily suspend the use of the vaccine this month. Most returned to administering the vaccine after European and UK drug regulators again endorsed the use of the vaccine, despite rare clotting problems, which have not been proven 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 deaths and serious illnesses and that its benefits outweigh the potential risks.

Much depends on the global acceptance of the AstraZeneca injection, which was co-developed with the University of Oxford and is the most widely used in many parts of the globe. The US Food and Drug Administration is due to review the trial data and can decide whether to authorize the use of the vaccine as early as next month.

The results of previous shooting tests in the UK and elsewhere have been criticized for the lack of elderly volunteers, who were later recruited in the testing process for safety reasons. The United Kingdom and other countries have used the vaccine over the age of 55, but some countries initially restrained themselves and only applied the vaccine to younger age groups.

The study in the USA involved 32,449 participants aged 18 or older, and about 20% were aged 65 or older. The vaccine was 100% effective in preventing serious diseases and hospitalizations, with similar results in all ages and ethnic groups.

The results of vaccine tests in the United Kingdom, released at the end of last year, showed a range of effectiveness, between 62% and 90%. That range was difficult to compare with the results of US tests of rival vaccines, one from Pfizer Inc.

and BioNTech SE from Germany and another from Moderna Inc.

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

The test results in the USA have not yet been reviewed by independent researchers. AstraZeneca said the analysis will be sent for publication in a peer-reviewed newspaper.

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

The AstraZeneca vaccine trial in the United States, which began recruiting volunteers in the United States, Chile and Peru in August, has been standardized to meet FDA guidelines, measuring the results of two doses four weeks apart. AstraZeneca said that increasing the doses – which the UK and other countries have done – could further increase the vaccine’s effectiveness.

The results of US final-stage tests provide the closest comparison between the AstraZeneca vaccine and the rival injections that were the first to be adopted in the USA. Clinical tests have shown that Pfizer and Moderna injections are more than 94% effective against symptomatic Covid-19.

Meanwhile, tests conducted by Oxford for the AstraZeneca-Oxford vaccine last year in the UK and Brazil have produced a confusing range of results, ranging from 62% to 90%, depending on dose size and timing.

Real-world vaccination data, heavily dependent on the UK. mass implementation has since shown that a single injection 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 to increase immunity, resulting in about 80% effectiveness among people aged 70 and over after the second injection. British researchers said the result was similar to the more than 70 results of the Pfizer-BioNTech vaccine.

The developing world is relying heavily on the AstraZeneca-Oxford injection, with 3 billion doses promised without profit this year. But public health experts have been concerned about the results of complex tests over the past year and AstraZeneca’s prolonged tension with European authorities over extreme deficiencies in vaccine delivery targets could permanently damage the vaccine’s reputation.

These factors and errors by AstraZeneca in its public and regulatory communications last year could impact perceptions of the vaccine in the United States, said some experts and analysts at AstraZeneca.

In late February, the United States authorized Johnson & Johnson’s Covid-19 vaccine for the American market, bringing a third injection to the nation’s vast supply chain. This single dose was found to be generally safe and 66.1% effective in protecting people against the development of moderate and severe cases of Covid-19 at least 28 days after vaccination, based on a study of around 44,000 volunteers aged 18 years or more.

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

But many people who want a vaccine cannot get it. Stocks of the AstraZeneca vaccine cannot be distributed in the United States until the injection is authorized by the FDA.

Last week, the Biden government announced plans to send 4 million doses of the AstraZeneca vaccine stored in the United States to Canada in Mexico, as a loan before a potential authorization. Officials said no deal was finalized.

The United States said it had 7 million “releasable doses” of the AstraZeneca vaccine. In total, the United States 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 accelerated vaccine production to meet domestic targets, including promoting manufacturing partnerships between vaccine manufacturers and increasing funding to streamline 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 supply goals. Stepped approvals, production deficits and export battles have complicated the launch. AstraZeneca executives said they are solving problems in the supply chain and plan to meet the announced obligations.

Following reports of blood clotting in Europe, regulators said last week that they will add a warning to the guidelines for use and patient information sheets for the vaccine, for healthcare professionals and people receiving the injection, to be on the lookout for signs of rare so-called thromboembolic problems – including a severe brain disease that caused a very small number of deaths in people who received the vaccine – and continued to support the injection. But regulatory authorities emphasized that there was no proven link between the vaccine and clotting problems, which also occur naturally in the general population and, in many cases, in Covid-19.

Write to Jenny Strasburg at [email protected]