Delays, blood clots, bans: What's plaguing AstraZeneca’s COVID vaccine?

Gayatri Vinayak
·6-min read
New Delhi, India- 16 January 2021. A health worker holding a dose of Covishield vaccine at a hospital during a campaign of vaccination in Delhi.
New Delhi, India- 16 January 2021. A health worker holding a dose of Covishield vaccine at a hospital during a campaign of vaccination in Delhi.

Studies, published in the New England Journal of Medicine, have found that certain antibodies are the cause behind the, sometimes potentially fatal, blood clots being reported in recipients of the AstraZeneca COVID-19 vaccine.

Recently, European Union’s medicine regulator, the European Medicines Agency (EMA) and the World Health Organisation (WHO) had said that there is a ‘plausible but not confirmed’ link between Vaxzevria, the coronavirus vaccine developed by Swedish, British company AstraZeneca in conjunction with the British University of Oxford, and the instances of rare blood clots.

With cases increasing exponentially across the world (133 million and counting) and India alone accounting for 12.9 million cases, all hopes have been pinned on the vaccines. AstraZeneca, in particular, was hailed as the slayer of the virus. 

The vaccine can be stored and transported at normal refrigerated temperatures of 2 degrees to 8 degrees Celsius. Further, its ramped up manufacturing ability meant that it could be effectively distributed around the world, at a low cost. Covishield, which is what the vaccine called in India, is one of the two vaccines being used currently in the country, the other being the indigenous Covaxin, manufactured by Bharat Biotech. 

The problems that the vaccine has encountered does not undermine its efficacy – data provided by the manufacturer shows an efficacy rate of 63 per cent. However, the troubles that have followed AstraZeneca ever since it announced its interim trial data, have eroded its reputation.

Shots of trouble

We take a look at all the problems that have plagued the vaccine:

Trial data dispute: In November 2020, AstraZeneca published an interim analysis of clinical trials report stating that its vaccine had an average efficacy of 70 per cent. While this led to much relief and cheer, it was later revealed that the figure of 70 per cent was obtained from combining different doses. 

AstraZeneca revealed three sets of data – average efficiency of 70 per cent, a high of 90 per cent and a low of 62 per cent. When a smaller group of people (3,000) received half the planned dose and then a full dose a month later, the results were promising – 90 per cent efficacy. However, a larger set (9,000) who were given two full doses, a month apart, showed a lowered efficacy of 62 per cent. 

While this did not affect the trials and AstraZeneca admitted that the half-dose was an error, the lack of communication proved to hit its reputation.

Efficacy issues for over-65s: In January, the drugmaker had to defend its vaccine from reports from various European countries that it had a low efficacy rate of between 8-11 per cent among those above 65. The fact that this is the main risk group, made the allegations more serious.

Following the reports, Germany’s vaccine committee recommended that the vaccine be restricted to those between the age groups of 18-64, as there was not enough data to analyse the efficacy for those above 65. 

It was only after the EU drugs regulator approved the use of the vaccine for all age groups that France, Germany and other countries revised their stand and approved its use for people above 65. 

Supply concerns: Earlier this year, the European Union suggested that the drugmaker restrict supplies to the UK after AstraZeneca announced a shortfall in planned COVID-19 vaccine shipments to the EU. The company had started its EU delivery in February and had committed to supplying the EU with 180 million doses.

On its website, AstraZeneca said that half of the EU’s supply in the second quarter and 10m doses in the first quarter were due to be sourced from the Company’s international supply chain. However, export restrictions affected the deliveries in the first quarter. It said that despite the delays, it aimed to deliver 100 million doses in the first half of 2021, of which 30 million are to be delivered in the first quarter.

In March, the United Kingdom warned that there would be a delay in the rollout of the vaccine to its under-50 population due to supply issues. The UK blamed delivery delays by Pune’s SII for the delay in its immunisation programme.

Indonesia has also said that it would face delays in its immunisation programme, as the country would only receive 20 million doses of the vaccine, instead of the initially agreed 50 million doses.

AstraZeneca has sent a legal notice to the Pune-based Serum Institute of India (SII) over delays in supplying its vaccines. This comes after SII delayed shipment to the UK and was unable to meet its obligations to other countries that were supposed to receive them.

On its part, SII has asked the Government to provide financial assistance after India imposed export restrictions, in order to boost its production capacity. Adar Poonawala, chief executive of SII said that the Government pays it less per dose than what it would earn from exports.

Blood clot woes: Adding on to its existing woes were the few reports of people who had been administered the shot in March, developing blood clots. While the cases were far and few between, it was enough to dent the vaccine's image and cause a number of countries to suspend its use, pending a safety review.

Bans: Amidst concerns over reports of blood clot in some of the recipients of the vaccine, a number of countries have either banned its use or have restricted it to certain age groups. Germany, Denmark, Spain, Norway, The Netherlands Italy, France, Sweden and Latvia are among the nations that suspended the rollout of the vaccine in March.

Thailand became the first country outside of Europe to delay its rollout initially but then went ahead after its Prime Minister received the first dose on March 16th. Belgium set an age limit on the vaccine and has restricted its use to people over the age of 55. The UK has also advised against rolling out the vaccine for its under-30 group and has said that they be offered an alternative. 

Meanwhile, South Korea has said that it would resume the administration of AstraZeneca vaccines for those between the ages of 30- 60.

With vaccine hesitancy growing, these issues and the frequently changing guidelines in many European countries over the vaccine, have led to much confusion and growing fear among people. 

Despite all the hiccoughs, however, the EMA and the World Health Organisation (WHO) have said that the benefits of the shot outweigh the potential risks. With vaccines of other manufacturers including Moderna and Pfizer being difficult to store, transport and more expensive, most countries are relying on AstraZeneca to help with the current health crisis.