Covishield vaccine has had more benefits than risks, says study by Kozhikode doctors

At a time when the safety aspects of the Covishield vaccine have kicked up a row, a retrospective study by two doctors from Kozhikode has claimed that its risks are minimal in view of the benefits.

The findings of the study are now being peer-reviewed ahead of their publication in a reputed medical journal. T. Jayakrishnan, head of the Department of Community Medicine, and Sruthi Krishna, senior resident, KMCT Medical College, Kozhikode, are the authors.

The controversy arose after pharmaceutical company AstraZeneca admitted in the High Court of London, United Kingdom, that its vaccine against COVID-19 had the potential to cause thrombosis with thrombocytopenia syndrome, a rare side-effect associated with blood clotting in the brain. The vaccine, developed in association with the University of Oxford, was distributed in India under the label Covishield.

The study examined the severe adverse reactions reported between January 16, 2021, when the vaccine was launched in the country, and May 17, 2022. Adverse reactions are classified as the unintended or harmful reactions to medicines in a particular time period. As many as 1.91 billion doses were given across India during then.

A total of 3,023 adverse reactions, including allergic reactions, blood clotting, and cardiovascular events, were reported, according to government data. Of them, severe adverse reactions were 1,527. The total number of deaths were 592. However, the study points out that only 11 deaths, which make up only 2% of the total number, were consistently associated with the administration of the vaccine and others were coincidental. Also, of the serious adverse events, only 270, around 18%, were vaccine-product related and 788 others, almost 51%, were coincidental.

Dr. Jayakrishnan pointed out that vaccine-induced thrombocytopenia in European countries was reported to be four per one million. Due to COVID-19 infection or disease, it is 25 to 60 per one million. In India, however, vaccine-induced thrombocytopenia as per government reports, is four per 10 million or one crore. It is only one-tenth of what is reported in the West. According to the World Health Organisation, adverse reactions, if any, with vaccines, will happen within six weeks. In India, almost 90% of the population received one type of vaccine or the other during 2021- 2022. There was no chance of adverse reactions in the future, he added.