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AstraZeneca vaccine data possibly 'outdated'

March 23, 2021

Coronavirus vaccine information from AstraZeneca may have provided an incomplete view of test results, a US regulator has said. The vaccine has been dogged with doubts about possible side effects.

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A woman receiving a coronavirus jab with AstraZeneca vaccine
Public trust in the AstraZeneca vaccine has fallen, though health officials recommend its continued useImage: Soeren Stache/dpa/picture alliance

The US National Institute of Allergy and Infectious Diseases on Tuesday expressed concern that "outdated information" could have skewed the results showing the efficacy of AstraZeneca's coronavirus vaccine.

The announcement comes one day after interim data from the British-Swedish drugmaker showed the vaccine was 79% effective in preventing symptomatic illness in a large trial conducted with adults in the United States, Chile and Peru and 100% effective against severe or critical forms of the disease and hospitalization. The data also did not point to increased risk of blood clots using the vaccine. Several European countries, including Germany, had temporarily suspended the use of the AstraZeneca vaccine amid fears it caused blot clots related to several deaths

A woman is tested for COVID-19 in Essen, Germany
Increased coronavirus testing in Germany aims to break chains of infection as vaccination efforts continueImage: Rupert Oberhäuser/picture alliance

What are the US regulator's concerns?

The US National Institute of Allergy and Infectious Diseases (NIAID) in a statement "expressed concern that AstraZeneca may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data."

"We urge the company to work with the (Data Safety Monitoring Board) to review the efficacy data and ensure the most accurate, up-to-date efficacy data be made public as quickly as possible," the NIAID statement said.

"This is likely a very good vaccine," Dr. Anthony Fauci, US President Joe Biden's COVID-19 medical adviser and NIAID director, told ABC News' Good Morning America program. "If you look at it, the data really are quite good but when they put it into the press release it wasn't completely accurate."

Based on earlier data, the European Medicines Agency, the EU's drug regulator, last week declared the AstraZeneca jab safe to use.

How did AstraZeneca respond?

AstraZeneca stood behind the data it released, saying in a statement on Tuesday that it included cases up to February 17, as required. The pharma company said it would "immediately engage" with US regulators and release its most up-to-date vaccine efficacy data within 48 hours.

"We have reviewed the preliminary assessment of the primary analysis and the results were consistent with the interim analysis," the company statement said. "We are now completing the validation of the statistical analysis.

The firm also said it would continue to analyze outcomes that have occurred since the February 17 cut-off date.

Why are people worried?

More than a dozen European countries, including Germany, France and Italy, suspended use of the AstraZeneca vaccine amid fears it caused blot clots in a small number of recipients. Following approval for continued use by the EMA, AstraZeneca vaccinations have resumed in Europe.

AstraZeneca said on March 14 that there had been 37 reports of blood clots out of more than 17 million people vaccinated in the 27-country European Union and Britain. The company added that the international study's independent safety monitors found no serious side effects associated with the vaccine, including the rare blood clots like those identified in Europe.

A team of researchers in Germany said it discovered what triggers the thrombosis and suggested a targeted treatment. 

Where is the AstraZeneca vaccine being used?

Developed by British-Swedish pharma giant AstraZeneca and Oxford University, the vaccine has received conditional or emergency use approval in more than 70 countries. It is currently being used across the European Union as well as in the United Kingdom. It is one of the four vaccines that have been approved for use in the EU.

The World Health Organization also approved the vaccine's use last month. The United States is expected to issue a decision on an application for emergency use in the coming weeks.

South Korean President Moon Jae-in on Tuesday received a dose of the AstraZeneca vaccine, joining several other high-ranking politicians who have either received an AstraZeneca jab or in a move to show the vaccine's safety said they would.

South Korean President Moon Jae-in receives a dose of the AstraZeneca COVID-19 vaccine at a health care center in Seoul
South Korean President Moon Jae-in joined several leaders willing to receive a dose of the AstraZeneca vaccineImage: Lee Jin-wook/Yonhap via AP/picture alliance

sms/msh (Reuters, AFP, AP)