Q. Is there a blood test to determine susceptibility to blood clotting issues post-vaccination?

Answered by
Dr. Mubashir Razzaq Khan
and medically reviewed by iCliniq medical review team.
This is a premium question & answer published on Jun 11, 2021

Hello doctor,

I am a 56-year-old female, and I am in the post-menopausal period for about eight years. I want to vaccinate, but I do not want the mRNA vaccines. For one reason (of a few reasons), I cannot wrap my head around the fact that they have tried bringing those types of vaccines or medicines to the market for years and have never been able to because of various problems and adverse side effects. Then all of a sudden, COVID-19 happens, and within a few months, we have two vaccines that have supposedly passed all of this testing. I do not feel safe taking those. I want to get the Johnson and Johnson vaccine, but I am worried about the blood clotting issue. I want to find out if a blood test is available that will give an idea if we are susceptible to the blood clotting issue. Thank you for your time.



Welcome to

I hope you are doing well in the pandemic.

All vaccines have adverse effects on a few (not all) individuals. The clotting problem is hyped in the media. In millions of doses given to individuals, the clotting problem is reported hardly in double figures (and not triple-figure). However, specific individuals have a history of clotting, thrombosis, bleeding, etc. They should be screened for clotting defects. In normal people, no such tests are required. Other minor side effects of the vaccine are extremely milder than the COVID-19 itself. So it is highly recommended that you get vaccinated with any vaccine available as early as possible.

Please do get back for further details.

Stay safe. Regards.

Thank you doctor for the advice,

I understand what you are saying regarding the side effects. However, a few years ago, my aunt went to a hospital, and they gave her a heparin shot, and she developed a blood clot in her hip, which they said was related to the heparin shot. So can you please tell me the name of a blood test that I could get to make sure I do not possibly have an issue with the vaccine? Thanks.



Welcome back to

Glad to see you back. The history of your aunt is incomplete. Did they find the underlying cause of the clot? Sometimes unfractionated heparin induces the production of antibodies in the host, which is associated with thrombotic tendency.

As far as the tests are concerned, PT (prothrombin time), aPTT (activated partial thromboplastin time) tests are prescribed for screening, as these tests measure the clotting tendency of blood. These tests are more sensitive to bleeding disorders due to clotting protein deficiencies. However, in thrombotic tendency (clotting formation in blood vessels), these tests result in normal ranges with a positive history.

In addition, after vaccination, we can measure the clotting tendency in terms of breakdown products of clots. For this purpose, a D-dimer test is recommended. So get a D-dimer test done on the fifth day post-vaccination. If found raised, get back to me.


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