Preparing for vaccines as a higher-weight person

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As updated COVID vaccines and this year's flu vaccines roll out, I got a request from several readers to post about the need for longer needles for higher-weight people’s vaccinations.

I’ve posted about this in the past and I’ll link to those posts at the end:

The short version is that these vaccines are intramuscular, meaning that they must be deposited into the muscle in order to have maximum efficacy. Because muscles have more vascularity/drainage they quickly and efficiently transport vaccines which maximizes effectiveness and also minimizes side effects. If, instead, the vaccine is deposited into the subcutaneous adipose tissue (ie: fat pad) above the deltoid muscle they will not reach maximum efficacy because there’s not enough vascularity/drainage and so the vaccine won’t be transported efficiently. This also increases injection site side effects like redness, bumps, and pain. 

All of this means that higher-weight people likely require longer needles in order to deposit the vaccine in the muscle. 

Per the CDC guidelines for adults age 19 and older:

22-25 gauge
130 lbs (60 kg) or less - 1 inch (25mm)
130–152 lbs (60–70 kg) - 1 inch (25mm)
Men, 152–260 lbs (70–118 kg) - 1 -1.5 inch (25-38mm)
Women, 152–200 lbs (70–90 kg) - 1 -1.5 inch (25-38mm)
Men, 260 lbs (118 kg) or more - 1.5 inches (38mm)
Women, 200 lbs (90 kg) or more - 1.5 inches (38mm)

There are some important limitations here. First, the study that these come from (completed in 1997) included only cis men and cis women with no trans or nonbinary representation. Also note that the final categories end with “and up.” This is because they reflect the range of weights that were included in the study. More research is needed that includes trans and nonbinary people as well as people at higher ends of the weight spectrum, and people of color.

You may want to call ahead to your preferred vaccination site to make sure that they have 1.5 inch needles. You may also have to do some self-advocacy - I have heard of healthcare practitioners who were nervous to use the 1.5inch needle so helping them understand that this will both increase efficacy and decrease injection side side effects may be helpful. You’ll also want them to press the skin down and pull it tight or just leave it as is, rather than pinching the skin outward.

I have some resources to help with this:

Printable cards that request a longer needle and provide links to the CDC guidelines and the original study as well as scripting that you can use:
https://weightandhealthcare.substack.com/p/how-to-get-the-correct-size-needle

Detailed two-part explanation of the issue:
https://weightandhealthcare.substack.com/p/vaccines-and-fat-people-a-history

Information to deal with the (likely misinformation) that prefilled vaccine syringes can’t be offered with 1.5 inch needles:

https://weightandhealthcare.substack.com/p/case-study-weight-stigma-impacts 

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More research and resources:
https://haeshealthsheets.com/resources/

*Note on language: I use “fat” as a neutral descriptor as used by the fat activist community, I use “ob*se” and “overw*ight” to acknowledge that these are terms that were created to medicalize and pathologize fat bodies, with roots in racism and specifically anti-Blackness. Please read Sabrina Strings’ Fearing the Black Body – the Racial Origins of Fat Phobia and Da’Shaun Harrison’s Belly of the Beast: The Politics of Anti-Fatness as Anti-Blackness for more on this.