A class-action suit in the United Kingdom has spotlighted the Covid-19 vaccine from AstraZeneca-Oxford University combine, and the risk of blood clots and low platelets possibly linked to this vaccine.

AstraZeneca (AZ) is reported to have said in court documents that the vaccine could “in very rare cases, cause TTS” (thrombosis with thrombocytopenia syndrome), according to UK media reports. The company is facing a class action suit from a small number of families affected by the vaccine, which it is contesting, the report said.

The rare blood clot risk linked to the AZ Covid-19 vaccine had been flagged in early 2021. And several European countries and Canada, for example, restricted the use of the vaccine in sections of their populations as cases emerged. In 2022, the British Medical Journal (BMJ) too had flagged this small but increased risk to TTS, linked to the AZ-Oxford vaccine.

Responding to the UK developments, AstraZeneca said, “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.”

India’s Serum Institute has an alliance with AZ on this vaccine, produced and sold in India as Covishield. It accounted for a major share (over 170 crore) of the estimated 220 crore doses administered in the country. The company did not comment on the recent development.

“Not new”

The World Health Organisation’s former Chief Scientist, Dr. Soumya Swaminathan, told businessline, that information on the vaccine’s side effects were “not new” and several international regulators had reviewed its risk-benefit ratio and streamlined their vaccination programmes. Adverse events linked to vaccination would have shown up within 4-8 weeks of vaccination; besides, the risk of clotting from the Covid-19 infection was high, she added.

Dr. Swaminathan, presently Chairperson of MSSRF, also pointed to the WHO’s “no fault compensation” programme, a limited vaccine injury compensation system in low and middle-income countries for COVAX-distributed vaccines.

Eminent virologist Dr. T Jacob John observed that the risk-benefit ratio was in the vaccine’s favour during the pandemic, especially for those with co-morbidities and senior citizens, who were faced with the risk of mortality and hospitalisation.

Countries “not worried about finding data” streamlined their vaccination programmes based on data, and a good public health system picked up the adverse events, Dr John said, calling for a comprehensive, public health-oriented adverse event reporting system.

Families had gone to the courts in India too, seeking compensation for the deaths of family members allegedly linked to the Covid-19 vaccine.

India’s Health Ministry has not commented on the latest developments in the UK.