Thermostability of Measles and Rubella Vaccines in a Microneedle Patch

Measles and rubella vaccinations are highly effective at reducing disease prevalence; however, logistic issues related to subcutaneous administration and vaccine wastage limit the extent of vaccination coverage. Microneedle (MN) patches can increase coverage by easing logistics through simplified administration and improved stability. This study demonstrates the thermostability of a bivalent measles and rubella vaccine MN patch. Rubella vaccine stability required pH buffering during drying; potassium phosphate buffer at neutral pH was optimal for both vaccines. Screening 43 excipients for their ability to retain potency during drying and storage yielded sucrose-threonine-potassium phosphate buffer formulation at pH 7.5 as an optimal formulation. MN patches made with this formulation had no significant loss of vaccine titer after one month and remained within a one log₁₀ titer loss cutoff after 3 - 4 months at 5°C, 25°C and 40°C. Finally, these patches were shown to be immunogenic in juvenile rhesus macaques. This work demonstrates the potential for MN patches for measles and rubella vaccination to be removed from the cold chain, which is expected to decrease vaccine cost and wastage, and increase vaccination coverage.