CDC Advises Use of Longer Needles for Certain Vaccinations

According to the Centers for Disease Control and Prevention (CDC), individuals with larger body sizes may benefit from longer needles for vaccinations.

Recent social media conversations highlighted that people with bigger bodies might get a more effective vaccination—like the COVID-19 vaccine–if administered with longer needles.

However, despite these suggestions from health authorities such as the CDC, experts are concerned it may not always be applied in practice.

Matthew Laurens, MD, MPH, a researcher at the University of Maryland’s Center for Vaccine Development, expressed uncertainty about the level of adherence to these updated recommendations.

Amesh Adalja, MD, a biosecurity and emerging infectious diseases specialist from John Hopkins Bloomberg School of Public Health, proposed that healthcare workers could occasionally use the wrong needle length for individuals with larger body sizes.

Adalja recommended that people who are overweight or obese confirm the correct needle length for their body size with the administering healthcare provider.

Details of who would benefit from a longer needle length for their vaccination were also provided.

Intramuscular vaccines, like the COVID-19 jab, are administered into the deltoid muscles on the shoulders. However, these muscles are covered by skin, fat, and connective tissue, which can differ in thickness among individuals, as explained by Adalja.

Therefore, different needle lengths are recommended depending on the patient's body size.

“Intramuscular [vaccines] require an advancement of the needle beyond the subcutaneous layer,” Laurens stated.

Aside from more effective vaccination, using a suitable needle length can also minimize potential side effects such as swelling or redness at the injection site.

The CDC guidance suggests that healthcare providers use a scale to determine the appropriate needle length for adults aged 19 and above.

The CDC emphasizes that intramuscular injections should involve needles long enough to reach the muscle mass without contacting underlying nerves, bone, or blood vessels.

However, not all vaccines are administered intramuscularly, leading to diverse needle length requirements depending on the vaccine recipient.

There have been online posts about people not being offered the correct needle length for their body size when getting vaccinated at a pharmacy.

As ideal needle lengths can vary depending upon body weight, Laurens advised checking with the healthcare provider to ensure the right needle length is used during vaccination.

However, discerning the needle length that a healthcare provider intends to use after preparing the vaccine can be difficult, hence it's better to discuss this ahead of the vaccination.

Receiving a vaccination with the incorrect needle length doesn't necessarily mean it will not provide protection, but it may not provide optimal protection, Adalja noted.

Vaccines administered with the wrong needle length might still elicit a degree of immune response, which contributes to a certain level of protection.

The method of vaccination, including the needle length used, can impact its effectiveness.

For example, the vaccine might still reach the correct area, the deltoid muscle, if the administering healthcare provider applies extra pressure, even if the needle length was not ideal.

“It's possible the vaccine delivery may not have been as effective, and it might not work optimally—but it's not an all-or-none phenomenon,” said Adalja.

In an ideal situation, all CDC guidelines, including appropriate needle length recommendations, should be followed, particularly for delivering the COVID vaccines, Laurens asserted.

“We need to evaluate the implementation of these guidelines,” he added. “It definitely requires attention.”

For this reason, it’s worth double-checking the needle length with your healthcare provider before receiving your vaccination. This can ensure you’re getting the maximum possible protection and might also benefit future patients.

“I think it’s great to be as informed as possible about the vaccine, including the length of the needle,” Laurens said. “The more informed we are, and the more we hold each other accountable, the better outcomes we have.”