A recent class-action suit in the United Kingdom has put the spotlight on the AstraZeneca-Oxford University combine’s Covid-19 vaccine, and the possible risk of TTS (thrombosis with thrombocytopenia syndrome) linked to this vaccine.

The multinational company is reported to have said in Court documents that the vaccine could “in very rare cases, cause TTS”, according to UK media reports. The company is facing a class action suit from a small number of families affected by the vaccine, the report said.

The risk of TTS (blood-clots and low platelets) possibly linked to the AZ Covid-19 vaccine had been flagged in several countries, over the last two years. And several European countries and Canada, for example, had restricted the use of the vaccine in its older or younger population, as the cases emerged.

In a statement to businessline, AstraZeneca said that “From the body of evidence in clinical trials and real-world data, the AstraZeneca-Oxford vaccine has continuously been shown to have an acceptable safety profile and regulators around the world consistently state that the benefits of vaccination outweigh the risks of extremely rare potential side effects.”

The multinational added, “Our sympathy goes out to anyone who has lost loved ones or reported health problems. Patient safety is our highest priority and regulatory authorities have clear and stringent standards to ensure the safe use of all medicines, including vaccines.”

India’s Serum Institute has an alliance with the AZ, on this vaccine. It produced and sold the vaccine in India under the brandname Covishield, which accounted for a major share (over 170 crore) of the estimated 220 crore doses administered in the country. A response is awaited from the vaccine major, on the recent developments in the UK.

When global reports of blood clots emerged, early 2021, regulatory officials in India said, they were reviewing the adverse events linked to the vaccine. The Health Ministry has not yet commented on the recent developments from the UK, involving the vaccine.

However, families had gone to the Courts in India too, seeking compensation for the death of family members allegedly linked to the Covid-19 vaccine.

BMJ study

In 2022, the  British Medical Journal (BMJ) had flagged this small, but increased risk to TTS, linked to AZ-Oxford vaccine.

A study published in the BMJ showed a 30 per cent higher risk in developing rare blood clots from the AstraZeneca Covid vaccine, compared to Pfizer’s mRNA vaccine. This, at a time, mRNA vaccines were also making headlines worldwide, over possible links to cardiac-events.

Based on health data from five European countries and the US, the BMJ study showed a small increased risk of TTS after a first dose of the Oxford-AstraZeneca vaccine, and a trend towards an increased risk after the Janssen/Johnson & Johnson vaccine, compared with the Pfizer-BioNTech vaccine, the journal had said.

When the data was pooled together, “analysis showed a 30 percent increased risk of thrombocytopenia after a first dose of Oxford-AstraZeneca compared with Pfizer-BioNTech – an absolute risk difference of 8.21 per 100,000 recipients”, according to the study. Though the condition may be very rare, these observed risks needed to “be considered when planning further immunisation campaigns and future vaccine development”, the researchers had said.