SAN DIEGO (KGTV) -- Some newly published research suggests the rare cases of heart inflammation linked to the COVID-19 vaccines might be caused by an accidental injection in the wrong spot.
All of the authorized vaccines are designed to be injected into a muscle, not a blood vessel.
Research published in the journal Clinical Infectious Diseases in August found mice injected with mRNA into a vein developed heart inflammation, called myopericarditis. Mice injected in the proper location, the muscle, did not.
Although experts are cautious about drawing conclusions from animal studies, the paper has unleashed a long-simmering debate about whether healthcare providers should take additional steps to ensure a needle doesn’t inadvertently enter a vein during vaccination.
However, even doctors in favor of additional precautions say inadvertent injection in a vein is extremely unlikely. Providers inject the COVID vaccines into the shoulder, where there are few large blood vessels nearby.
“I think this is an important study because it gives us one possible mechanism that we can try to chase down,” said UC San Diego professor Dr. Robert Schooley, who is the editor of the journal that published the research.
The authors proposed that vaccine providers use a technique called aspiration. It works like this: after the needle enters the skin, the provider briefly pulls back the plunger. If the needle happens to be in a vein, the syringe will draw up droplets of blood, a visible clue for the provider to remove the needle before injecting mRNA.
The technique used to be commonplace in the U.S. and globally, but many countries stopped recommending the practice in recent years.
“I think most people in the UK and the United States are giving the vaccines wrongly,” said Dr. John Campbell, a retired nurse lecturer in the UK who advocates for aspiration, in a YouTube video viewed more than 335,000 times.
“This really has to change,“ he added.
However, other experts say previous research on plunger withdrawal found it had more drawbacks than benefits.
“You have to leave the needle in longer,” said Dr. Kirk Knowlton, the director of cardiovascular research at Intermountain Medical Center Heart Institute in Salt Lake City, Utah. “It gets jiggled around a little bit. It’s more painful.”
Dr. Knowlton said tweaking the injection method sounds simple, but it would require new training on a large scale.
Many experts question whether there is a need to adjust the vaccination technique in the first place. Myocarditis occurs about twice after every 100,000 injections. On top of that, research shows it’s typically mild and resolves quickly.
“I think that gives us a pause before we drastically and dramatically change our overall strategy,” Knowlton said.
However, the study on mice has prompted some countries to revisit their recommendations. Denmark and Hong Kong now instruct providers to pull back the stopper to check for blood before injecting vaccines.
“I think it’s something that we should consider from a public health perspective,” Dr. Schooley said. “I think that the inconvenience of it is actually relatively minimal. We’ve got the personnel to do it. And it would be a good way to test this hypothesis.”
The researchers behind the study hypothesize mRNA might inadvertently enter a vein, sending instructions to cells in the heart that temporarily provoke unwanted immune activity in that area. They demonstrated that the heart cells in mice produced spike proteins, but there has been no such evidence in humans.
Dr. Knowlton, who specializes in mice studies, said the theory was intriguing, but cautioned that other factors could be at play.
The mice received a very large dose of mRNA and their immune systems function slightly differently, he said.
He said the findings should ultimately reassure the public that the risks from myocarditis, regardless of the method of vaccine administration, are exceedingly low.
“Even when they gave it intravenously, the mice did surprisingly well,” Knowlton said.