Challenges to assuring client eligibility and appropriate dosing at mass vaccination clinics

Background/Purpose: The 2009 H1N1 influenza pandemic tested public health efforts to vaccinate a susceptible public. Eligibility criteria and the mix of available vaccine were complicated. We evaluated mass vaccination efforts in Snohomish County, Washington.

Methods: The local public health agency collaborated with hospitals, major clinics, pharmacies, tribes, and third party payers to administer H1N1 vaccine through mass vaccination clinics (MVCs) on two days. Written consent forms documented eligibility and presentation of vaccine administered for all vaccinees.

Results/Outcomes: Nine MVCs were held on 10/24/09 (vaccinating 5,429 persons) and ten on 10/31/09 (vaccinating 20,185 persons); one drive-through MVC operated on both days. Eligibility could be verified for 88% of vaccinees on 10/24/09 and for 95% of vaccinees on 10/31/09. The correct presentation of vaccine (based on age, pregnancy status, and underlying chronic disease) was administered to at least 94% of pregnant women, 97% of children <24 months old, 77% of children 24-59 months old, 81% of persons aged 2-49 years without contraindication to intranasal vaccine, 87% of children 24-59 months old, 96% of persons aged 2-49 years with contraindication to intranasal vaccine, and 97% of adults ≥ 50 years old.

Conclusions: MVCs can efficiently vaccinate many people in short periods, but may not be able to fully restrict eligibility or to assure administration of the appropriate vaccine when eligibility criteria are complicated. Simplifying eligibility criteria may reduce potential errors in vaccine administration.