Americans of all shapes and sizes will flock to pharmacies and doctors’ offices this fall to receive flu and Covid vaccines, but they may not know that size matters when it comes to the needle that goes into their arms.
Centers for Disease Control and Prevention the guide stipulates that men and women up to about 150 pounds should receive a one-inch-long needle.
But adults weighing more than 200 pounds will need a longer needle, about an inch and a half, to penetrate fat and deep muscle tissue.
Fat people are already disproportionately more likely to get sick from Covid, compounding the problem.
Most people without healthcare experience may not realize that needle length is important, which means very few know to even discuss it with their doctor or pharmacist.
The injection needle used must pass through the adipose or fatty tissue to reach the muscles where the content of the injection, that is, the Covid vaccine, is deposited.
Dr William Schaffner, an infectious diseases expert at Vanderbilt University, told DailyMail.com: ‘Doctors don’t want to run the risk of the vaccine not being an immunization for their patients if they are older. Therefore, use a larger needle when giving intramuscular vaccines.
Recommending that vaccine administrators consider a person’s weight when choosing the length of needle to use is not new. Health professionals learn it in school and at work.
The CDC has said for years that the decision about needle length “should be made for each person based on muscle size, the thickness of fatty tissue at the injection site… and the depth below the muscle surface in which the material is introduced”. is going to be injected.
However, that guidance is not widely used in practice.
Dr. Schaffner said, “I don’t think the average person would have thought about that.” Once you do it and think about it for five seconds, you won’t be too surprised.
‘It shouldn’t be up to the patient to bring that up. However, cooperation is always good and if a patient is aware of this, it would be good to discuss it in a friendly and helpful way.’
Some studies estimate that doctors who vaccinate overweight and obese people get the needle length wrong up to 75 percent of the time.
Using a needle slightly longer than the standard one-inch length for an overweight person gives the drug a better chance of penetrating fatty tissue and depositing it in muscle, which is the target of a vaccine.
According to the CDC: ‘The appropriate needle length depends on age and body mass. The injection technique is the most important parameter to ensure efficient intramuscular administration of the vaccine.
“For all intramuscular injections, the needle should be long enough to reach the muscle mass and prevent the vaccine from leaking into the subcutaneous tissue, but not so long as to affect the underlying nerves, blood vessels or bones.”
While the length of the needle is important, most people without healthcare experience may not realize it. That means very few people in line for a booster with their sleeves rolled up are likely to even know to discuss it with their doctor or pharmacist.
Population surveys have consistently shown that injection professionals use the wrong size needles. In 1997, a study showed that standard one-inch needles failed to penetrate deltoid muscles in 17 percent of men’s arms and 48 percent of women’s.
A 2013 study in the journal Research in applied nursing found that among all patients surveyed of all weights, only 50 percent of injections were administered correctly. And in overweight and obese patients, that error rate reached up to 75 percent.
Getting the wrong size needle could make the vaccine less effective, although the evidence on this is conflicting.
A 2010 study published in the journal Pediatrics sought to determine how body mass index and needle length influence the effectiveness of the hepatitis B vaccine, which, like the Covid and flu vaccines, must be administered deep into the muscles.
Obese teens who received the vaccine through a 1.5-inch-long needle had a significantly higher antibody response than those who received the injection through a one-inch needle.
Meanwhile, a study published in the May 2023 issue of Nature medicine He argued that the length of the needle did not change the effectiveness of the Covid vaccine.
The researchers determined that the peak antibody response was actually higher in obese people who received the injection with the same needle length as non-obese people, although their immunity tended to wane more quickly.
Obese people who have a body mass index of 30 or more should get vaccinated against Covid and flu. Obesity significantly increases the risk of contracting a severe case of Covid and has been shown to triple the risk of being hospitalized.
The CDC reported in spring 2021, around the one-year anniversary of the outbreak that started it all, that about 78 percent of all people who had been hospitalized, needed 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 could be attributed to one of four chronic conditions, including obesity, to which 30 percent of cases were attributed, the majority, as well as high blood pressure, diabetes and heart disease. failure.