Revaccination management of a large cohort of pediatric patients following a potential lapse in cold storage.

Introduction: In a pediatric clinic in California (US), 3823 patients were vaccinated with potentially-compromised vaccines following lapses in cold storage chain management between February 2014 and April 2015. A revaccination program was initiated in May 2015. Families were contacted by mail and encouraged to discuss follow-up options with their care team, namely: revaccination, serological testing and/or revaccination, or no further action. This study aimed: to understand which families were more likely to respond to the outreach, and to engage in any testing and/or revaccination; to determine whether or not vaccination with these potentially-compromised vaccines elicited sufficient immune response in pediatric patients; and to estimate the program cost.

Methods: Patients who had received potentially-compromised vaccines were identified, and relevant data were extracted from their electronic health records. Logistic regression analyses were performed to identify factors associated with response to outreach, serological testing and/or revaccination.

Results: 3823 patients between 0 and 21 years received an average of 3.1 potentially-compromised vaccines. 2547 revaccinations were performed (1515 patients) and 544 patients had serological testing results. Non-immune titer levels were only reported for 3-4% and 8% of the tested patients who had received potentially-compromised tetanus and hepatitis B vaccines, respectively, and only for children two years old and younger. Three years after the revaccination program started, 77% of all cases were considered resolved and 62.5% of patients (1970/3152) who were administered potentially-compromised vaccines were either revaccinated or had seroprotective titers. Response to outreach and decision to choose serological testing and/or revaccinate were affected by patient age, race/ethnicity and zip code median income (p < 0.05).

Conclusion: We observed race/ethnicity, patient age and income differences in response to the outreach and decision-making. For patients vaccinated with potentially-compromised vaccines, serological testing should be considered prior to revaccination. Revaccination may not be the most appropriate course of action for all patients.