India should examine Covishield after reports of blood clots after vaccination

A man wearing a protective mask walks past COVID-19 graffiti on a street in Navi Mumbai, March 8, 2021. Photo: Reuters / Francis Mascarenhas / File Photo.

New Delhi: Indian drug regulators are expected to review data on one of two candidate vaccines in their national COVID-19 vaccination campaign after reporting that some vaccine recipients complained of unusual blood-related illnesses.

The Covishield vaccine candidate is derived from the AZD1222 vaccine developed by researchers at the University of Oxford and licensed to AstraZeneca Plc, an Anglo-Swedish drug maker. The Indian company Serum Institute has a contract with AstraZeneca for the manufacture of Covishield doses and a purchase agreement with the Indian government.

Last week, Denmark, Norway and Iceland suspended the rollout of AZD1222 doses after some recipients reported low blood platelet counts and blood clots. Italy and Austria also took note.

Sigurd Hortemo, doctor of the Norwegian Medicines Agency, said Reuters that they had not yet determined whether the three cases reported in their country were related to the vaccine.

AstraZeneca has yet to comment on the concerns – although they compound a series of existing issues the company is already facing. The most important of these is his dispute with the EU over supply issues.

The news

“During the active phase of a COVID-19 infection or after COVID-19, there is inflammation of the blood vessels with a propensity for clots to form,” said Dr. CN Manjunath, director of the Institute Sri Jayadeva from Bengaluru Cardiovascular Sciences. The Hindu in January 2021.

“It can cause heart attacks. However, because the vaccine contains inactivated virus, it is immunogenic “and” produces antibodies but not inflammation “.

At 9:10 a.m. on March 14, 2021, the website of the Union’s Department of Health announced that 29.7 million doses of the vaccine had been administered.

NK Arora, a member of the national COVID-19 task force, told AFP the body was considering “all adverse events” and that there were “no immediate concerns” due to the number such events in India, compared to the population. , is “very, very low”.

There have been reports of Covishield vaccination followed by heart attacks, but not necessarily causing them:

* Moradabad, January 17

* Ballari, January 18

* Nirmal, January 20

* Shivamogga, January 20

* Bhangrola, January 23

* Ranchi, February 2

In a heart attack or myocardial infarction, part of the heart does not receive blood and the heart muscle is damaged. Cardiac arrest occurs when the heart suddenly stops beating and can be caused by a heart attack.

MAPI reports

According to India Spending, the Department of Health and Family Welfare provided only incomplete information on adverse events following vaccination until February 26 – and no reports since then.

The last of these missives indicated that 46 people had died after being vaccinated and 51 had been hospitalized. India Spending also noted that post-mortem procedures had only been carried out in some cases and the government did not yet have all investigation reports (at the time).

According to Arora, who spoke on March 13, there have so far been “50 to 60” deaths following vaccination. He also said the government treated them all as “coincidences”.

The series of reports of blood issues with the AstraZeneca vaccine is linked to its underlying technology.

Vaccine technology

The Covishield Vaccination Platform, or AZD1222, uses an adenovirus vector. Researchers take an adenovirus and “delete” some of its genes that allow this virus to replicate. They also add genes to allow the virus to make the spike protein for the novel coronavirus.

When this adenovirus is injected into a body, the virus invades a cell and releases its genes. They hijack the cell’s biological machinery and start producing the spike protein for the novel coronavirus.

Once the spike protein is expressed on the surface of the cell, the body’s immune system takes note and begins to attack and destroy the affected cells. In the process, the immune response also develops a “memory” for the spike protein.

So the next time another virus invades the body and has a spike protein – like the novel coronavirus – the immune system might react seriously, before an infection sets in.

Scientists around the world have been working on adenovirus vector vaccines for many decades and at that time recognized a potential problem with this technology.

The effectiveness of the vaccine could be affected if a human body has developed resistance, or even immunity, to the adenovirus vector itself. Satyajit Rath, immunologist at the Indian Institute of Scientific Education and Research in Pune, said The Hindu that studies have not yet definitively resolved the debate.

However, Rath and Jacob John, an epidemiologist formerly at Christian Medical College, Vellore, agreed that increasing the dosage of the vaccine could overcome this obstacle.

This may be necessary since AZD1222 is a double dose vaccine and may need to be administered annually to recipients to ensure that the human body maintains an appropriate level of resistance to COVID-19 infections.

Such repeated vaccination will also repeatedly expose the body to the adenovirus vector and encourage the body to develop an immune response against it.

Other potential solutions include giving recipients a mixture of adenovirus vector vaccines – such as AZD1222, Johnson & Johnson’s jab, and Russian Sputnik V. This is because these vaccines use different types of vaccine. adenovirus vectors and elicit different immune responses.

Sputnik V uses different adenovirus vectors – Ad5 and Ad26 subtypes – in each shot, potentially increasing the immune response without allowing the body to become familiar with the vector.

Inactivated virus vaccines like Covaxin, the other candidate vaccine in the Indian countryside, and mRNA vaccines like the Pfizer and Moderna vaccines do not have this problem and can be administered repeatedly.