HKU study warns against accidental vaccination into veins

Local | 22 Aug 2021 6:51 pm

Accidental intravenous injections of BioNTech jabs may cause heart muscle inflammation, research conducted by the University of Hong Kong has found.

The team advised that those who administer jabs briefly withdraw the syringe plunger to exclude blood aspiration to ensure that the needle is not accidentally in a vein before the injection is given.

According to global statistics, 50 per million doses of mRNA vaccine including BioNTech ones could trigger myocarditis or pericarditis – inflammation of the heart muscles and tissues surrounding the heart. The  12 to 29 age group is more prone to the condition, especially after the second dose. But most patients rapidly recovered from this potentially life threatening side effect, and mRNA vaccines are deemed safe, with the risks markedly outweighing the side effects.

But research led by Dr. Can Li, Dr. Anna Zhang and Professor Yuen Kwok-Yung pointed that accidental intravenous injection could trigger heart conditions.

In the study, researchers injected the mRNA vaccine into the thigh muscles of mice via the standard intramuscular routes and compared the outcomes with those of mice injected with the intravenous route.

“We found that the heart of those mice receiving intravenous vaccine developed obvious myocarditis and pericarditis within 24 to 48 hours. This heart damage is greater even after a second dose of vaccination 14 days later,” according to the team.

The hearts of mice which received intramuscular injections saw no such damage, leading the team to believe that accidental intravenous injections may cause the heart conditions.

“As health authorities have previously advised that there is no need to aspirate a needle before injection, there is a risk that in rare circumstances, the injection may inadvertently be injected intravenously,” the team said.

“We therefore advise that the practice of intramuscular injection should revert to the conventional way. That means a brief withdrawal of syringe plunger to exclude blood aspiration to ensure that the needle is not accidentally located in a vein before the injection is given.”

Another possible method to reduce risk is to change the injection site from the shoulder muscle to the lateral side of thigh muscle, they added.

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