Besides the Covid-19 vaccine, do other vaccines cause blood clots?

To learn more about this issue, a reporter from the Health and Life Newspaper interviewed Associate Professor Dr. Pham Quang Thai, Deputy Head of the Department of Infectious Disease Control, Central Institute of Hygiene and Epidemiology.

Causes of blood clots after receiving the AstraZeneca Covid-19 vaccine.

Reporter: Professor Pham Quang Thai, what are the causes of blood clots after receiving the AstraZeneca Covid-19 vaccine?

Assoc. Prof. Dr. Pham Quang ThaiBlood clots commonly occur in people with thrombotic conditions, where there are problems with the immune response, and the body produces antibodies that can bind to one of the body's natural proteins. This protein is called platelet factor 4 (PF4). In fact, when infected, many people produce antibodies that can bind to PF4 as part of their immune response, but these antibodies are often weakly adhesive.

In people who experience blood clotting after vaccination, the antibodies formed can bind very tightly to PF4, forming larger structures called "immune complexes." These complexes bind together and activate platelets. Normally, platelets float in the blood in an inactive state, but once activated, they form a "net" that creates blood clots.

Can blood clots occur with other vaccines?

Reporter: So, does this side effect occur with other common vaccines, Professor?

Assoc. Prof. Dr. Pham Quang ThaiThis phenomenon can also occur when there is an antigen-antibody reaction. Thus, not only with the Covid-19 vaccine, but also with other vaccines or in cases of infection.

In fact, there was once a recorded case of a child being born with numerous blood clots in the lungs because the mother contracted chickenpox during pregnancy. That child died about 30 minutes after birth.

However, this rate is very low, even in European communities it is very rare (European communities have a high rate of spontaneous thrombosis (up to 10/million/21 days) compared to other communities, especially when compared to Asia where this rate is extremely low (less than 1/million/21 days).

Which individuals are more susceptible to blood clot formation after vaccination?

Reporter: Which groups are at higher risk of developing blood clots after vaccination, expert?

Assoc. Prof. Dr. Pham Quang Thai:In healthy individuals, the rate of blood clots after vaccination is very low. This risk may be higher in people with a history of blood clotting disorders. These cases are carefully examined and monitored by doctors before, during, and after vaccination to ensure safety.

Is there a need to worry about blood clots after receiving the AstraZeneca Covid-19 vaccine 2-3 years ago?

Reporter: Expert, now that the majority of the population has received the AstraZeneca Covid-19 vaccine 2-3 years ago, is it still possible for this side effect to occur?

Assoc. Prof. Dr. Pham Quang Thai:The issue of blood clots is primarily observed within 28 days after vaccination, and mostly after the first dose. Therefore, there is no need to worry about side effects leading to blood clot formation. Currently, many people unnecessarily go to medical facilities to have blood clotting tests done, simply out of concern about the side effects of the Covid-19 vaccine.

People need to seek out official information and avoid anxiety and panic... The information that the Covid-19 vaccine can cause blood clots is not a new or unusual issue. However, taking advantage of this opportunity, many "anti-vaccine" groups have spread misinformation on various social media channels, so people need to be vigilant and avoid unnecessary misunderstandings.

Interviewer: Thank you, Associate Professor!