COVID-19 Needle Length Study

COVID-19 vaccines are intended for injection into the deltoid muscle in the arm. However, previous research shows the standard needle used for vaccination in Aotearoa New Zealand does not reach the deltoid muscle in many adults with larger bodies due to the layer of fat that sits between the skin and deltoid muscle.

It is currently unknown if vaccine delivery into the muscle is required to achieve full immune response from the vaccine, and whether side effects differ depending on where the vaccine is delivered.

In this study we will compare the immune response and side effects following COVID-19 vaccination delivered either into the muscle or into the fat below the skin. Any difference identified based on the location of injection will be important both in Aotearoa New Zealand and internationally.

What is this study about?

This study aims to assess whether immune response and side effects from COVID-19 vaccination differ depending on whether the vaccine is delivered into the deltoid or not. 

Participants will be randomly assigned to receive their COVID-19 booster with a short needle (into the fat) or with a long needle (into the muscle). 

During the study participants have an initial phone call with the study team, one pharmacy visit to receive the vaccination, and three blood tests at their local collection centre (before vaccination, at week 4, and week 15). At the pharmacy visit we will measure height, weight, and arm circumference. 

Participants will be compensated for their time and travel.

Who can take part? 

To take part you must:

✓ Have received at least two previous COVID-19 vaccines

✓ Be aged between 18 and 75 years old 

✓ Have a BMI of at least 30.2 (for women) or at least 37.3 (for men) 

✓ Be eligible to receive a COVID-19 booster

Who can’t take part? 

This study isn’t suitable for everyone, you would not be able to take part if:

x You have had a COVID-19 infection in the last 6 months

x You have received a COVID-19 vaccine in the last 6 months

x You have used any immunosuppressive medication in the last 4 weeks

x You are currently pregnant

Where is the study taking place?

  • Newton Pharmacy, 283 Karangahape Road, Auckland

    Ōtahuhu 7 Day Chemist, 15 Station Road, Ōtāhuhu, Auckland 1062

  • Life Pharmacy; Centre City Shopping Centre, 11 Gill Street, New Plymouth

  • Waitangirua Pharmacy, 201 Warspite Avenu, Waitangirua, Porirua 5024

  • Queen Street Pharmacy; 35 Queen Street, Upper Hutt Central, Upper Hutt 5018

  • Clive’s Chemist; 20/21 Queen Street, Wainuiomata, Lower Hutt 5014

    Unichem Petone Pharmacy: 240 Jackson Street, Petone; Lower Hutt 5012

  • Alexander Pharmacy, 191 Willis Street, Te Aro, Wellington 6011

  • Anderson’s Exchange Pharmacy; 8 Broadway, Central Dunedin, Dunedin 9016


More locations coming soon.

Enquire for more information

If you’re interested in taking part, please click the link below to complete our trial survey.

Alternatively, if we haven’t answered all of your questions here, please contact the study team for more information about the Needle Length Study.

needlelength@mrinz.ac.nz | +64 4 805 0246

Ethics: Ethical aspects of the study approved by the Health and Disability Central Ethics Committee (2024 FULL 18986)

SCOTT: The Standing Committee on Therapeutic Trials has granted regulatory authority for this study (2024 SCOTT 19171)