AstraZeneca vaccine: A timeline of the coronavirus jab under investigation over links to blood clots

Side effect described as ‘very rare’ by European Medicines Agency but concerns linger

British adults aged under 30 should be offered an alternative coronavirus vaccine to the Oxford-AstraZeneca jab if one is available in their area, the UK government’s vaccine advisers have said, as concerns linger that the shot could be linked to blood clots.

The Joint Committee on Vaccines and Immunisation made its recommendation on Wednesday as the European Medicines Agency (EMA) likewise warned healthcare professionals to “remain aware” of the possible side effect while saying it is “very rare”.

The Medicines and Healthcare Products Regulatory Agency (MHRA) is still investigating the phenomenon.

On Tuesday, a trial of the same vaccine in children was paused in the interests of safety. “We await additional information from the MHRA on its review of rare cases of thrombosis/thrombocytopaenia that have been reported in adults, before giving any further vaccinations in the trial,” an Oxford spokesman said of the decision, making clear that no blood clots had been discovered as part of its latest testing.

As the situation develops, here’s a reminder of the Oxford-AstraZeneca jab’s development and rollout over the last year.

Read more:

• Coronavirus news live: Latest AstraZeneca vaccine updates 
• UK regulator to give AstraZeneca blood clot investigation update 
• ‘Link’ between AstraZeneca vaccine and blood clots, EMA official says
• Are younger people at risk of blood clots linked to AstraZeneca vaccine?
• How worried should you be about possible AstraZeneca vaccine blood clot link?

30 April 2020

With the world in the grip of the pandemic, British-Swedish pharmaceutical giant AstraZeneca (AZ) develops a vaccine against Covid-19 that uses a modified chimpanzee virus to tell the human body to produce the coronavirus spike protein and trigger an immune system response.

18 May 2020

AZ signs a deal with Boris Johnson’s government to supply 30m doses by September and 100m by the year’s end.

21 May 2020

The US government under Donald Trump signs an equivalent deal to secure 300m doses and pays the company $1.2bn to bankroll clinical trials and manufacturing.

4 June 2020

AZ signs two major agreements with the international vaccine organisations, the Coalition for Epidemic Preparedness Innovations and Gavi, to provide 1.3bn doses to low and middle-income countries. The organisations agree to pay $750m to cover production costs on the first 300m doses, which they hope to receive before the year is out. AZ also signs a 1bn-dose deal with the Serum Institute of India.

20 July 2020

The company’s vaccine receives a key endorsement when The Lancet publishes the results of the University of Oxford’s initial phase I human clinical trials, indicating it is safe.

10 August 2020

Investors send AZ’s share price to an all-time high as it becomes the most valuable company on the FTSE 100 index, with its Oxford partnership announced and its vaccine in pole position to be world’s first.

1 September 2020

Large-scale Phase III human trials commence in US.

8 September 2020

Trials are abruptly halted after it emerges a UK volunteer has died of a serious neurological condition. An independent review board subsequently finds the symptoms were unlikely to have been caused by the vaccine but the company’s bungled handling of the news rocks confidence.

9 November 2020

Pfizer beats AZ to become the first major pharmaceutical company to announce the results of its Phase III clinical trials, saying its jab is 90 per cent effective.

19 November 2020

Oxford reports further data in The Lancet declaring its product is showing a particularly strong response in older test subjects.

23 November 2020

Oxford-AstraZeneca announce the results of their own Phase III clinical trials from the UK, South Africa and Brazil, citing a somewhat confusing “blended average” efficacy from the data of 70 per cent.

30 December 2020

Britain becomes the first country in the world to approve AZ’s vaccine for national rollout, a relief to millions frustrated with lockdowns.

25 January 2021

AZ’s feud with the EU begins when the company informs the bloc that it will only be able to supply its member states with about 40 per cent of the vaccine doses it promised in the first quarter of the year due to manufacturing complications. The EU demands it stick to its contract and considers imposing export controls to stop batches being sent on to post-Brexit Britain.

28 January 2021

German healthcare regulators question whether there is sufficient data on the AZ’s performance among the over-65s to merit its approval as French president Emmanuel Macron claims it is only “quasi-effective” in immunising the same age group.

29 January 2021

The EMA finally does approve the AZ vaccine, still raising doubts about its efficacy for older people.

3 February 2021

Oxford-AstraZeneca publishes further data in a bid to reassure Europe, saying a single dose cuts coronavirus transmission by about two-thirds and that it is 76 per cent effective.

5 February 2021

The partners say their vaccine is effective against the emerging UK variant of Covid-19, then causing particular alarm.

8 February 2021

South Africa, struggling with its own variant, says the AZ vaccine is ineffective at stopping mild to moderate Covid cases of the new strain and stops its rollout.

15 February 2021

Oxford-AstraZeneca commences its study of the vaccine’s impact on children.

22 February 2021

The Serum Institute of India asks the company to ramp up production for its own market, prompting fears of an export delay.

4 March 2021

Italy blocks shipments of AZ’s vaccine to Australia as alarm over Europe’s limited supplies intensifies.

5 March 2021

Germany changes its mind and approves the vaccine for over-65s.

11 March 2021

Denmark halts its rollout of the AZ jab over concerns about dangerous blood clotting, the first time the issue is raised.

16 March 2021

Germany, France and Italy follow Copenhagen’s example but the EMA and World Health Organisation insist the vaccine is safe, the former re-emphasising its opinion two days later following a review.

22 March 2021

AZ releases interim results from its latest American clinical trials, saying the vaccine proved 79 per cent effective against symptomatic Covid-19 and 100 per cent effective against hospitalisation and death.

23 March 2021

The US National Institute of Allergy and Infectious Disease, led by Dr Anthony Fauci, unexpectedly issues a middle-of-the-night statement sounding the alarm that AZ may have used “outdated” data that provided an “incomplete” picture of its vaccine’s effectiveness.

25 March 2021

AZ releases further results from its US trials, including more up-to-date data, showing that its vaccine is 76 per cent effective as part of a bid to allay fears among the public.

26 March 2021

The EU approves a new manufacturing plant for the continent in the Dutch city of Leiden, which will produce the AZ vaccine and hopefully improve the existing supply shortage.

30 March 2021

German cities and regions including Munich and Berlin suspend distribution of the AZ vaccine to people under the age of 60 over the ongoing blood clotting concerns. Canada also stops giving the vaccine to those under 55.

6 April 2021

The Oxford-AstraZeneca vaccine trial in children is paused as MHRA investigates the blood clots in adults, with the University of Oxford making clear that no problems had arisen within the trial itself.