Americans of all shapes and sizes are heading to pharmacies and doctor’s offices this fall to get flu and Covid shots, but they may not know that size plays a role when it comes to which needle gets stuck in their arm.
Centers for Disease Control and Prevention guidelines state that men and women weighing up to about 150 pounds should get a 1-inch needle.
But for adults over 200 pounds, a longer needle of about an inch and a half is needed to penetrate fat and deep muscle tissue.
Fat people are already disproportionately more likely to get Covid, compounding the problem.
The majority of people without experience in medical care may not be aware that needle length is important, which means very few people know how to even discuss it with their doctor or pharmacist.
The injection needle used must penetrate fat or adipose tissue to reach the muscles in which the contents of the injection, i.e. the Covid vaccine, are deposited.
Dr. William Schaffner, an infectious disease expert at Vanderbilt University, told DailyMail.com: “Doctors do not want to run the risk of the vaccine not immunizing their adult patients. Therefore, a larger needle should be used for intramuscular vaccinations.”
The recommendation that vaccine administrators consider a person’s weight when choosing which length of needle to use is not new. Health professionals learn this in school and on the job.
The CDC has said for years that a needle length decision for each person should be made based on the size of the muscle, the thickness of the fatty tissue at the injection site…and the depth below the muscle surface at which the material was detected. ” “is deposited.” . must be injected.’
However, this directive is not commonly used in practice.
Dr. Schaffner said: “I don’t think the average person would have even thought of that. If they do and think about it for five seconds, they won’t be so surprised anymore.
“It shouldn’t be up to the patient to bring it up.” However, cooperation is always good and if a patient is aware of this, it is good to bring it up in a friendly and helpful way.”
Some studies estimate that doctors who vaccinate overweight and obese people choose the wrong needle length up to 75 percent of the time.
Using a needle slightly longer than the standard 1-inch length in an obese person increases the chance that the drug will penetrate fat tissue and deposit it in the muscle, which is the goal of a vaccine.
According to the CDC, “the appropriate needle length depends on age and body weight.” Injection technique is the most important parameter to ensure efficient intramuscular administration of the vaccine.
An end to vaccine damage? New “smart” needle guides itself
Researchers at Brigham and Women’s Hospital have developed a needle that can “sense” differences in the resistance of different tissues and automatically stop if the needle goes too far.
“For all intramuscular injections, the needle must be long enough to reach the muscle mass and prevent the vaccine from penetrating the subcutaneous tissue, but not so long that it affects underlying nerves, blood vessels or bones.”
Although needle length is important, most people without experience in medical care may not be aware of it. This means that very few people queuing up for a booster shot are likely to even tell their doctor or pharmacist.
Population studies have consistently shown that professionals who administer injections use the wrong size needle. In 1997, a study showed that traditional 1-inch needles failed to penetrate the deltoid muscles in 17 percent of men’s arms and 48 percent of women’s arms.
A 2013 study in the journal Applied Nursing Research found that in patients studied of all body weights, only 50 percent of injections were administered correctly. And for overweight and obese patients, this error rate was as high as 75 percent.
Using the wrong size needle can reduce the effectiveness of the vaccine, although the evidence is mixed.
A 2010 study published in the journal Pediatrics sought to determine how body mass index and needle length affect the effectiveness of the hepatitis B vaccine, which, like Covid and flu shots, is intended to go deep into the injected muscles. to be administered.
Overweight teenagers who received the vaccine through a 4.5 cm needle had a significantly higher antibody response than those who received the injection through a 2.5 cm needle.
Meanwhile, a study published in the May 2023 issue of Nature Medicine argued that the length of the needle does not change the effectiveness of the Covid vaccine.
Researchers found that the maximum antibody response in obese people who received the injection with a needle of the same length was actually higher than in non-obese people, although their immunity tended to decline more quickly.
Overweight people with a body mass index of 30 or higher should still be vaccinated against Covid and flu. Obesity significantly increases the risk of severe Covid disease and has been shown to triple the risk of hospitalization.
In the spring of 2021, around the first anniversary of the outbreak that started it all, the CDC reported that about 78 percent of all people who were hospitalized, required a ventilator or died from Covid were overweight or obese .
And a 2021 study by researchers at Tufts University in Massachusetts concluded that 89 percent of Covid hospitalizations in November 2020 were due to one of four chronic conditions, including obesity — the largest, which accounts for 30 percent of cases proportion such as high blood pressure, diabetes and heart failure.
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Crystal Leahy is an author and health journalist who writes for The Fashion Vibes. With a background in health and wellness, Crystal has a passion for helping people live their best lives through healthy habits and lifestyles.
