Like many other Americans, in 2021, I volunteered at a mass vaccine site. Under a tent, a team of health care professionals loaded up syringes, which were then carried by staff to lines of cars, where vaccinators put the preloaded needles into arms. Every person got the same vaccine, the same amount, and the same size needle.
But different bodies need different length needles, and needle length can affect how well a vaccine ends up working in your body. If you are about to go get this year’s COVID vaccine, or really any vaccine, you’ll want to pay attention. If you are female identifying and over 200 pounds or male identifying over 265, you may need a longer needle—and in all likelihood, you’ll need to advocate for it.
The needle needs to reach your muscle
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Most vaccines work by being injected into muscle, and vaccinators typically use your deltoid. That’s the muscle in your upper arm, and the muscle resides under a layer of fat, which absolutely everyone has. Ideally, the needle—often one inch long for everyone from young kids to adults—penetrates the fat, and goes into the muscle.
But bodies are built differently, and if you have more fat over the muscle, one inch may simply not be long enough. For that reason, the CDC has long recommended that body size be taken into account while vaccinating, and adults receive needles from one inch to one-and-a-half inches long.
While body weight is one way of determining this need, body shape and size are the key. Vaccinators are charged with making the determination while consulting the patient prior to the vaccine. And the longer needle is not more painful—it’s not a wider circumference needle—so there shouldn’t be significant barriers to acting per the CDC guidelines.
How was I supposed to know about this?
It’s really not any patient’s job to know—we all fairly assume that when we get a flu shot or a vaccine, that the equipment used is the right equipment, and we don’t need to think about it. There’s good reason to believe that: After all, healthcare professionals have to go through education that includes this CDC recommendation.
During the pandemic, due to need, qualifications for vaccinators were lowered, but even in these cases, most vaccine sites required on-site training that should have included this CDC data.
The trouble is, weight bias in healthcare is prevalent and well-known. I interviewed six vaccinators who said they worked at mass vaccination sites across the U.S. during 2021. Only half of them knew about the CDC recommendation, and only one said they held to the recommendation and were armed with different-sized needles. I know at my mass vaccination site in Arizona in early 2021, we were not using different needle lengths. Most alarmingly, one of the other vaccinators suggested that despite knowing the recommendations, healthcare professionals negated the concerns. “I was a vaccinator at mass and small clinics and can tell you that weight guideline was resoundingly dismissed by doctors and nurses. I would let the vaccinators worry about this, not the patients. You will find most pharmacies will only use one size.”
I called three pharmacies distributing the current COVID vaccine: a CVS in midtown Manhattan, a Walgreens in Chicago, and a Rite Aid in Los Angeles, and spoke to the person who identified themselves as the pharmacy manager in each, asking if they were using different needle lengths based on weight for the current COVID vaccine. Only the Walgreens indicated that they were. The Los Angeles and New York locations both said they were using one-inch needles on everyone. When I asked them about the needle-length advisory, both seemed surprised by the information.
What happens if I don’t get a long enough needle?
We know that intramuscular vaccines should be injected into muscle, and that a one-inch needle doesn’t always reach the muscle. What’s less clear is how that translates to efficacy of vaccines, including the COVID vaccine. The way to measure this would be to run a titer, which measures the amount of antibodies or virus in the body after injection. With COVID, we don’t have good measurement tools, so there is no effective titer to run. But, in 2010, a study was run on adolescents with obesity who received a Hepatitis B vaccine. Longer needles led to 80% higher titer levels post vaccination.
That said, how a vaccine is administered counts, too. More experienced vaccinators might be able to inject at an angle that still penetrates the muscle. Regardless, there is no suggestion that vaccinations with shorter needles than advised are worthless. It’s still better to get a vaccine with a standard needle than not get one at all.
How do I know if I got a longer needle and how do I ask for one?
Needle length isn’t indicated on any record, so you’ll likely never know what length you received previously. Armed with this knowledge, though, you’d be better able to advocate for a longer needle, if you need it, in the future. I solicited Dr. Shradha Chhabria, co-author of the 2022 paper mentioned above, an MD specializing in obesity medicine, on her advice to patients who might need this additional needle length.
She explained that there is scientific foundation for the request, which should hopefully make speaking up easier. “This is a CDC standardized practice, that is irrefutable, and is part of any standardized vaccine training, per CDC guidelines,” Chhabria said. She advocated for patients to speak on their own behalf. “I think that anyone that goes to get their vaccine, who is aware of these weight-based guidelines and the fact that they may have improved immunity from the vaccine if the right needle length is used should feel very empowered to speak up and say ‘hey, my understanding is that the CDC recommends that for my weight, I use a 1.5-inch needle. Do you have any 1.5 inch needles available today?’ Any vaccinator should be able to see that’s the standard of care.”
If the vaccinator does not have the appropriate length needle, Chhabria advised asking if they’d be able to get one, but that ultimately, getting vaccinated with less possible efficacy is better than not doing so at all.