Dear all - Happy 2020!! I came across a relatively recent update to the Cochrane Review of Needle sizes for vaccination. I thought I'd share it with the TechNet Community. The full report is here: https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD010720.pub3/full

Cochrane Database Syst Rev. 2018 Aug 9;8:CD010720. doi: 10.1002/14651858.CD010720.pub3. "Authors conclusions:

Using 25 mm needles (either 23 G or 25 G) for intramuscular vaccination procedures in the anterolateral thigh of infants using the WHO injection technique probably reduces the occurrence of local reactions while achieving a comparable immune response to 25 G 16 mm needles. These findings are applicable to healthy infants aged two to six months receiving combination DTwP vaccines with a reactogenic whole-cell pertussis antigen component. These vaccines are predominantly used in low- and middle-income countries. The applicability of the findings to vaccines with acellular pertussis components and other vaccines with different reactogenicity profiles is uncertain."