Explained: Blood Clotting & Vaccines. Should India be Concerned?

'If clotting occurred in India, due to the clinical curiosity of the condition, doctors would have reported them.'


Recent reports of rare blood clotting issues in the Johnson & Johnson vaccine in the US, and in the AstraZeneca vaccine in Europe, have raised several questions about the safety of these vaccines.

In India, our inoculation drive against COVID-19 relies heavily on Covishield, the name under which AstraZeneca's vaccine is sold here by Serum Institute of India.

Is the J&J vaccine pause by the US drug regulators, as they investigate these adverse events largely seen in young women in the age group of 18-48, and Denmark's decision to completely stop the AstraZenenca vaccine, a reason for concern for us here in India?

FIT speaks with Prof K Srinath Reddy, Chairperson, Public Health Foundation of India, to understand the issue.


What happened with both AstraZeneca and Johnson & Johnson vaccines?

This particular complication has also been reported by AstraZeneca vaccine earlier in Europe, which led to some countries stopping it initially, and with some stopping its use in certain age groups, to more recently when Denmark completely stopped using the vaccine.

In Europe, it was noted that these complications occurred predominantly in young women under the age of 55, though some young men were also affected.

How rare are these blood clots?

These patients had clotting in unusual locations in one of the venous sinuses of the brain and in the large veins draining the intestines and other organs. Venus thrombosis do occur but these are not the usual sites. For example if someone takes a long flight, it may happen. The second element is that in these patients it was found that platelet counts was very low. Platelets are cells that are usually circulating in the blood and help increase clotting. Now, instead of bleeding, some one has clotting, that too in the venous side, it is a very unusual occurrence.

While there were some questions earlier if they were linked to the vaccines, over a time it became clear in Europe that it was linked to AstraZeneca vaccination, even though it was rare. With that information, when J&J demonstrated almost an identical feature in younger women, the regulatory authorities decided to pause the inoculations.

Both AstraZeneca and J&J vaccines are viral vector vaccines, is that a concern?

In these vaccines, the DNA code for the spike protein is carried by a so-called harmless virus, which is an adenovirus. In the case of AZ, it is a chimpanzee virus, in case of J&J, it is a human virus. Where is the fault? Is it is in the DNA that has come loose, and that is causing the problem? Or is the problem with the adenovirus itself? That needs to be looked at. The fact that all of them are adenovirus vaccines, it puts them in the same bracket of suspicion.

Sputnik V also uses human adenoviruses as a delivery mechanism. They've come up with a big explanation and said that our technique is very different and we don't have this kind of free floating DNA, and we are very safe. We really need to examine what is causing the problem with these vaccines.

Sputnik has been used internationally, but they haven't reported any such events.


India largely relies on Covishield for its inoculation programme. Why have we not heard of clotting issues here?

Because this is an auto immune reaction, we don't know if there are certain factors in the caucasian population, which are not seen in India, that are causing the reaction in young women there. We need to examine this. At the same time, we must ensure that all adverse events are fully monitored, catalogued and analysed and improve our adverse event monitoring.

But at the same time, if these events occur and occur in substantial numbers, due to the clinical curiosity of the condition, doctors would have reported the events, even if the government was not picking them up.

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