Program factors that were associated with vaccine uptake included the lead-time between allocation and ordering and shipping, and the type of providers receiving vaccine. Factors not related to program decisions such as health-seeking behaviors and population characteristics also contributed to predicting state-to-state variation, as would be expected given baseline variation in previous influenza vaccination coverage  and other findings ,  and . Lead-time
from allocation to ordering and shipment was negatively associated with vaccination coverage. Steps in the ordering process varied by state and could include requesting specific orders from providers (in advance of allocation or after receiving an allocation), decisions on where to distribute vaccine, and notification of decisions. States Quizartinib clinical trial also determined the frequency of ordering, the day(s) of the week to order, the number of providers participating or receiving vaccine, and the overall process to follow, all of which could affect the lead-time. Because of the initial focus on ACIP-defined target groups, in many states adults without high risk conditions were not eligible for vaccination until demand for vaccine
had already begun to wane. Delays in allocated vaccine being made available to the population could have resulted in less vaccination. On the other hand, lags in ordering could be a consequence of decreasing these demand, and thus be a result of lower vaccination rates rather than a cause. Tenofovir The tendency for lags in ordering to be consistent for a given state throughout the time period
studied, suggests the lead-time resulted from the ordering process. We also found a relationship with the type of providers or locations to which vaccine was directed. For adults, vaccine sent to providers with specialized services or patient base was associated with lower coverage. This could be because not all adults visit internists or specialists frequently enough to be vaccinated in this time period; it could also be that those providers had less focus traditionally on vaccinating so patients looked elsewhere for vaccine. Overall, only a small proportion of vaccine was sent to internists and specialists. One variable may be more a measure of health infrastructure than the supply chain system itself. In particular, the maximum number of sites to which vaccine could be directly shipped through the centralized distribution system) was positively associated with vaccination coverage. (In contrast, another variable measured the actual ship-to sites registered or used within a state.) The maximum number of ship-to sites allowed for each state was based on a formula that included the population size as well as the number of existing VFC providers. A high number of VFC sites per capita could be a reflection of a more robust infrastructure for providing vaccine.