Is faulty injection technique behind rare clot disorder reported post Covid vaccination?

Recent world research counsel that incorrect injection methods used to manage Covid-19 vaccines could also be a purpose behind incidences of blood clots being reported post vaccination.

If the technique of administering the injection is incorrect, the vaccine may get injected into the blood stream as an alternative of reaching the muscle. This can result in blood clots, well being consultants mentioned.

“If the tip of the needle doesn’t reach deep enough in the muscle or if it hits a blood vessel, the vaccine can be directly injected into the bloodstream. This is an extremely rare possibility. It can happen when the skin is pinched up by an inadequately trained health worker. Intra-muscular injections are supposed to be given without pinching up the skin, so that the needle tip reaches the muscle. When the skin is pinched up, the needle tip reaches only the subcutaneous tissue,” mentioned Dr Rajeev Jayadevan, a member of the Indian Medical Association’s nationwide Covid taskforce in Kochi, Kerala.

(Photo: Twitter/Dr Jayadevan)

Dr Jayadevan defined additional, “When that happens, not only is the vaccine not absorbed properly, but rarely it can hit one of the blood vessels that travel through the subcutaneous layer which is located between skin and muscle. This layer contains a network of blood vessels.”

“One more problem is that people have stopped aspirating [pulling back the plunger of the syringe] to check if they hit a blood vessel while giving intra-muscular injections,” he mentioned.

“Unfortunately, many updated guidelines [from pre-pandemic days] suggest that ‘aspirating for blood return in the syringe’ is no longer necessary. This leaves a small chance of missing an inadvertent intravenous injection. In the past, aspirating was standard practice to ensure that the tip of the needle had not hit a blood vessel,” Dr Jayadevan mentioned.

ALSO READ: Scientists identify why Covid-19 patients develop life-threatening blood clots

He defined that if the needle tip enters a tiny blood vessel on this method, which occurs solely within the rarest of rare circumstances, the vaccine will instantly enter the bloodstream and might probably trigger an acute response.

“Thus, there is a greater chance of the adenoviruses being injected directly into the bloodstream,” he mentioned. Sputnik V, Johnson & Johnson and the AstraZeneca vaccine are adenovirus vaccines. Across the globe, J&J and AstraZeneca vaccinations have resulted in some circumstances of blood clots. However, there’s little information about hostile reactions post Sputnik V vaccination.

Dr Jayadevan added, “This was originally proposed by Professor Neils Høiby from Denmark in March this year.”


Another examine executed on mice on the Munich University in Germany additionally means that this rare complication in adenovirus vaccines could possibly be occurring because of the vaccine being injected into the blood stream. Vaccine candidates of various varieties corresponding to AstraZeneca (adenovirus-vector), Pfizer (mRNA) and a placebo have been used to examine for outcomes following totally different routes of injection.

The preprint of the examine by Leo Nicolai and co-authors, posted on, highlighted unintentional intravenous injection as a possible mechanism for post-vaccination thrombotic thrombocytopenic syndrome (TTS) additionally referred to as vaccine-induced immune thrombotic thrombocytopenia (VITT).

“Our data provides first experimental support for the potential sequence of events that could lead to TTS in some patients: Thrombocytopenia might be a result of accidental intravenous adenovirus vaccine injection with ensuing platelet-adenovirus aggregation and activation with antibody formation. We recommend aspirating to check for blood in the syringe before injecting,” the authors mentioned.


The danger of vaccine-induced clots is greater in girls. The causes for this aren’t totally identified. Anatomically talking, the needle is extra more likely to miss the deltoid muscle and hit the subcutaneous tissue in girls.

Dr Jayadevan mentioned, “Women have greater deltoid fat pad thickness – which means they have a thicker layer of fat separating the skin over the shoulder from the deltoid muscle underneath than men.”
This means the needle has to penetrate deeper previous the pores and skin to “hit muscle” in girls.

The similar size needle is used for each women and men. This signifies that the possibility of lacking the muscle with the needle is greater in girls. There is printed proof that the possibility of the tip of the needle being within the subcutaneous tissue is thrice greater in girls.

Women might produce other physiological danger components for thrombosis too.


It has been noticed that the danger of blood clots following vaccination is decrease within the case of the second dose as in comparison with the primary.

“It is about ten times less common with the second dose. One of the likely reasons for this is prior exposure [first dose] to the virus and hence a milder immune response even if it enters the bloodstream inadvertently. In the case of the first dose, the body has never been exposed to the virus,” defined Dr Jayadevan.


1. Do not pinch pores and skin up. Instead, gently stretch pores and skin earlier than plunging the needle at a 90 diploma angle.
2. The needle tip must be within the muscle, not the subcutaneous tissue.
3. Aspirate gently earlier than injecting. Make certain you haven’t hit a blood vessel.

Denmark’s Statens Serum Institut has already issued a particular advisory relating to vaccination technique for all Covid-19 vaccines to forestall inadvertent injection into the bloodstream. The syringe must be aspirated to examine for blood earlier than injecting the vaccine.

ALSO READ: Decoded | What is vaccine passport and how you can get one

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